What is the thing most likely to keep a big league executive awake at night?
The answer might vary, but high up on the list for all of baseball’s decision-makers would surely be innings. Just plain, simple innings. As in, who is going to pitch them and for how long? That issue, by itself and before we even get into how well the innings are pitched, is the gnawing problem for all those who are charting a course for the coming season.
Never has that riddle been harder to grok than it is right now, less than a month before the 2021 regular season begins. The innings problem was already a priority to-do item for execs around the game before last season and has been for eons. It’s also a 21st-century kind of dilemma and, ironically, one for which baseball’s honchos have only themselves to blame. With teams leveraging advanced data more and more each year, and deploying small legions of analysts digging for every marginal edge, all run-prevention innovations seem to lead back to a common need: more pitchers.
That means building bullpens is more important — and complicated — than ever before. How many relievers will teams need and where will all those extra arms come from?
The usage patterns of pitchers have evolved on an accelerating trajectory. For the first part of this century, there was actually a bit of stability in how much teams leaned on their bullpens. If you look at three-year rolling averages from 2001 up through 2015 — when the Kansas City Royals won a World Series on the back of historic bullpen production — you find that roughly 34% of batters faced were by relief pitchers. There was some year-to-year vacillation, but that was kind of the center point of the divide.
Then analysts around the game grew in number and, thanks to the advent of tracking systems such as Statcast, the data exploded and the age of the reliever truly dawned. The three-year average percentage of batters faced by relievers was 34 or 35 in each season from 2003 to 2016. Last season, that number was 43%. Consider the year-over-year growth over the past decade.
Here are the rising percentages of batters faced by relief pitchers each season during that span:
2011: 33%
2012: 34%
2013: 34%
2014: 34%
2015: 35%
2016: 37%
2017: 38%
2018: 40%
2019: 42%
2020: 45%
Last season, 735 pitchers saw action in a big league game, according to Baseball-Reference.com. That tied 2015 for the fifth most in history. The six highest totals have been the past six seasons, with each season setting a new standard until 2020. Ah, but as you surely recall, last year was a strange, surreal, unprecedented season in which teams played only 37% of their normal schedule. And yet we saw more pitchers throw a pitch in the major leagues than had in any season through all of baseball history up to 2014.
The total number of pitchers (some of them position players forced into action) grew from 799 in 2018 to 831 in 2019. It’s hard to say where the 2020 figure would have ended up without the pandemic, as it’s not a number that can simply be prorated. Given the recent rate of growth, the number likely would have ended up around 870.
This year, the total number of pitchers required to navigate a full 162-game slate — one year after the pandemic-truncated 2020 season — is likely to be north of 900. Which, if you’re scoring at home, is an average of at least 30 pitchers per team. And teams will have to come up with those hurlers even though the weirdness of 2020 will yield consequences of a type that can only be described with a question mark.
Because of the shortened season, starting pitchers at the big league level did not work up to their full innings count or anywhere close to it. Compounding this problem is the fact that there was no minor league season in 2020. Most of the development done by pitching prospects happened for the lucky few who were able to work in relative secrecy at each team’s alternate site, at which there were only so many spots to go around.
Clearly, there has never been a season for pitching like 2020. This is not the kind of problem that will be answered by the start of the 2021 season. It’s a drama that will play out day by day over the next six months.
Where will all these relievers come from?
In the 2020 season, as mentioned, 735 pitchers saw action. Of those, 599 made at least one appearance in relief, with 158 of those pitchers also making at least one start. (For our purposes today, we are not flagging starts made by openers.) Where did those 599 relievers come from?
Simply put, they came from everywhere. Here is a breakdown of what the primary job description for each of those 599 relievers was in 2019, or just one year earlier, and the number of each who appeared in the league ln 2020:
MLB reliever (228)
This would seem to be the obvious category, right? A big league reliever in 2020 is a pitcher you would on average expect to have been a big league reliever in 2019. And while that is by far the most common job description, it is far from the default job description. In fact, this category accounts for less than half the pitchers who made relief appearances in 2020.
One thing to keep in mind when reading this breakdown: There were more than 228 pitchers who made relief appearances in both 2019 and 2020. For the purposes of classifying pitchers by job description, we looked at two questions: At what level did the pitcher spend the majority of his time in 2019? And which role — starter, reliever or swing — did he occupy?
Thus many pitchers occupied more than one role in both seasons, and many pitchers pitched at more than one level in 2019. The job descriptions here refer to the role they occupied most frequently in a given season. Thus there were 228 relievers last season whose primary job description in 2019 was also MLB reliever.
Minor league reliever (121)
This seems logical as well. There is a lot of attrition in the ranks of relievers, and even without minor league teams in action last summer, teams still were able to dip into their organizational depth and transition some of their 2019 relief prospects to the majors. The standout in this category is the reigning NL Rookie of the Year. Milwaukee’s Devin Williams spent most of his 2019 season in the minors before breaking through in a big way last season.
Still, at this point, we’ve accounted for only 349 relievers, leaving 250 who didn’t come from the obvious talent pools.
Minor league starter (102)
Versatility is a key trait for a young pitcher trying to transition from the minors to the majors, now more than ever. Thus many of those who were flagged as a minor league starter were in fact swing candidates right from the start. Those pitchers tend to end up as lower-leverage innings sponges and spot starters. However, some pitchers do follow a path from a minor league rotation to a leveraged bullpen role in the majors.
A prime example of that last season was St. Louis’ Genesis Cabrera. Cabrera started in 18 of his 20 minor league appearances during his first season in the Cardinals’ organization in 2019 before breaking in as one of those spot-starter/multi-inning reliever types later that season. In 2020, Cabrera was a force in the back of the St. Louis bullpen, ranking third on the club in win probability added.
Minor league swingman (38)
While this group is not large in number, it is large in impact. Of the 38 pitchers who landed in this bucket, 14 of them were used in medium-to high-leverage roles last season.
Some pitchers might end up here without being true swingmen, but they are still a group to watch. For example, Kansas City’s Josh Staumont started in 12 of his 32 minor league appearances in 2019 and finished up in 11 others. He never threw more than two innings in any of his starts. Nevertheless, after breaking in for K.C. late in 2019, he emerged as the Royals’ top reliever last season and one of baseball’s most vicious hurlers in general.
Other impact relievers from last season who fell into this bin included Jonathan Hernandez of the Rangers, Brusdar Graterol of the Dodgers, Enoli Paredes of the Astros and Alex Reyes of the Cardinals.
MLB swingman (37)
Mostly these were pitchers who weren’t quite starters and weren’t quite relievers in 2019, then filled a similar role in 2020. However, pitchers can occupy crucial roles coming from this group, often in hybrid roles that help glue a 2021-style staff together. Among standouts in this class in 2020 were Chad Green of the Yankees, Matt Wisler of the Twins and Freddy Peralta of the Brewers.
MLB starter (31)
Sometimes when things aren’t working out in the rotation, a pitcher can find his way working in shorter stints and trimming his arsenal of pitches. The famous example of this is probably Hall of Famer Dennis Eckersley, but many pitchers have taken this route. That said, in 2020, this group didn’t appear to feature many such promising second-chancers. Mostly it was populated by starting pitchers who ended up throwing in relief because they were needed to soak up innings and landed in this capacity because they were struggling as starters. Not a lot of Eckersley stories in 2020.
Position player (17)
By our count, there were 17 position players called on for mound duty in a game their team was losing in a rout last season. It’s a relief appearance, technically, but teams don’t design their rosters for this. They only hope the need for it never arises.
Injured list (12)
Injury returnees always have to be viewed with caution when it comes to pitching, but many times they do return and do well. The star of this class in 2020 wasn’t technically coming back from injury. Rockies righty Daniel Bard was one of the feel-good stories of a feel-bad season, coming out of retirement to serve in a high-leverage capacity in an otherwise shaky Colorado bullpen. Bard had not pitched in the majors since 2013 after succumbing to the yips more than a half decade before.
International starter (5)
International reliever (4)
Every season, we get a few pitchers from leagues around the world who join the MLB party and make an impact. Some of them last season were of the traditional type, who built strong résumés overseas before making the move stateside. There wasn’t a whole lot in terms of bullpen value in that class in 2020. Kwang-Hyun Kim came over from South Korea and was so-so as a reliever before doing well in the St. Louis rotation. Meanwhile, Shun Yamaguchi put up an ERA of 8.06 for the Blue Jays.
Others in this group include players who go overseas and get better before returning to MLB to show their new stuff. We saw some interesting contributors of that ilk in 2020, such as Toronto’s Rafael Dolis and Houston’s Brooks Raley.
Indy league reliever (3)
From the leave-no-stone-unturned class: Tyler Matzek of the Braves, as well as Brandon Leibrandt and Brett Eibner (both with the Marlins). All three went from an unaffiliated league to the big leagues in 2020. Eibner was a position player during his earlier time in affiliated ball, which included 244 big league plate appearances. Leibrandt, son of Charlie, missed all of 2018 and 2019 with injury before signing with an independent league last spring. He got some time with the Marlins when Miami was inundated with COVID-19 cases.
Matzek is the true rags-to-riches story here. Before 2020, he had last pitched in the majors for Colorado in 2015. He played briefly for three affiliated teams in 2019 but spent most of his season toiling for the Texas AirHogs of the independent American Association. Last season, he ended up with the Braves, led all Atlanta relievers in strikeouts, posted a 2.79 ERA and was fantastic during seven postseason appearances.
Incidentally, expect this pool of talent to expand at the big league level in the years to come. With MLB slashing the number of affiliated teams from 160 to 120, the quality of talent in independent leagues should be stronger than it has been in decades.
Amateur swingman (1)
We’re talking Garrett Crochet of the White Sox here, who went from the University of Tennessee to the first round of the 2020 draft to the White Sox bullpen over the span of a few months. Obviously, pitchers of this type aren’t too easy to find.
So again we ask: Where do relief pitchers come from? Well, they can literally come from anywhere, from almost any level and from almost any corner of the planet. That, too, is why executives lose so much sleep over the innings problem.
How many relievers will teams need?
Teams don’t know. They don’t know how many pitchers they will need in a normal season. And given the added complications stemming from the pandemic, they sure as heck don’t know how many pitchers they’ll need this season.
Just look at the evolution of the sixth inning over the past 20 seasons. For years, the sixth inning has been something of a balancing act for big league managers. It’s too early to bring out the ace-level relievers, but starters by that point in the game might be tiring, or might be seeing the opposing lineup for the third time in a game. This last consideration has become a larger factor in recent seasons thanks to analytics.
As a result, and quite gradually, going to the bullpen has become nearly the default choice for managers in or before the sixth inning. There are thankfully plenty of exceptions, and these days fans appreciate a starting pitcher going seven innings as much as they used to appreciate a workhorse going the distance. Still, consider the percentage of sixth-inning batters faced by relievers over the past 20 years, figures based on data from TruMedia:
The numbers were pretty steady through 2014, when all of a sudden starting pitchers began to see a whole lot fewer hitters in the sixth inning. By 2019, more than half of all sixth-inning plate appearances in the majors came against the opposing bullpen. That number exploded in 2020, though the degree of that number is surely exaggerated because so many pitchers weren’t stretched out when the season began. Still, this is a stark trend.
While teams have better tools than ever to evaluate pitchers, the problem of putting together a bullpen has hardly gotten easier. Think back to a graphic that kept popping up during the 2020 playoffs showing the array of arm angles from which Tampa Bay’s relievers could attack the opposition.
The frozen image was reminiscent of a mandala, one of those beautiful designs drawn with colored grains of sand by Tibetan monks. Awe-inspiring as those designs are, as with bullpens, the images are fleeting. When, after days of work, the monks finish their designs, they wipe them away, to begin again in another time and place.
That’s kind of how it is with building bullpens. Of course there are some teams that seem to be better at it than others, but even those clubs often do it with a revolving cast. Consider the makeup of the bullpen for the champion Dodgers, who on paper project to be one of the strongest teams in history. But for all the talent in L.A. and the payroll tab that goes along with it, Blake Treinen and Tommy Kahnle are the only relievers on the roster with guaranteed dollars coming their way beyond this season, and Kahnle got a two-year deal only because the Dodgers are helping him rehab during the first season of the contract after he underwent Tommy John surgery.
For every team and in every season, there are only a handful of bullpen pieces that are stable from one campaign to the next. And that’s if you’re one of the lucky ones.
The starting point for every bullpen is the back of it — the high-leverage hurlers to whom managers turn in the most crucial situations. And the turnover of those roles is less than that for the lesser roles. That only makes sense — you have to be somewhat established to land a back-of-the-bullpen job, and if you get one, chances are you have the kind of talent to hold that job for a while, health permitting.
You can classify bullpen roles in different ways, but for this analysis, we flagged 59 relievers as high-leverage stoppers for 2020, about 10% of all relief pitchers. Of those, 46 were MLB relievers in 2019, or 78% of our high-leverage guys. This was a fairly standard rate of year-to-year turnover. In other words, if you’re a high-leverage reliever one year, there is a fairly good chance you’ll at least be an MLB-level performer the next season.
Thus the vast majority of free-agent relievers this winter who landed multiyear contracts were recent MLB, high-leverage performers. Think Liam Hendriks, Ken Giles, Pedro Baez, Jake McGee, Treinen, Kahnle, Trevor Rosenthal and Trevor May. These pitchers have enough demonstrated stability to garner such a commitment. Though it should be noted that Hendriks’ three-year deal with the White Sox was the only deal for more than two years handed out to a free-agent reliever during the offseason.
When you shift down a class to medium-leverage pitchers, the rate of attrition really starts to pick up. Last season, only about 60% of the 115 pitchers tagged as medium-leverage by this methodology spent most of their 2019 seasons in the majors. Again, this is a fairly standard rate of turnover.
After that, forget about it. If you’re a low-leverage reliever this year, there isn’t a great chance you were a major leaguer last year. In recent years, the rate of turnover for that classification has run about 50%.
Overall, just 64% of the 698 pitchers who made at least one relief appearance in 2019 appeared in the majors in any capacity last season. Of the 659 relievers in 2018, only 51% made it to 2020. Of the 610 relievers who saw action in 2017, only 41% were still around in 2020. And so on. The number drops steeply each season you go back.
In fact, let’s consider 2015. In theory, if you were a rookie in 2015 and spent most of each of the past six seasons at the big league level, you’d have six years of service time and thus would be eligible to hit the free-agent market. Relievers rarely accrue service time at such an ideal rate, but let’s go with it for a moment.
In 2015, there were 565 pitchers who made at least one relief appearance. Only 27% of them appeared in the big leagues in 2020. The vast majority of career relievers will never last long enough to reach free agency, though many will end up there anyway because they’ve reached the end of their usefulness to their previous organization and there are other pitchers pushing up behind them. Life as a reliever is tough. Being one might be the quickest and surest path to getting to the big leagues in the first place, but it’s not the best way to enjoy a long career.
And yet, teams need relievers. They need lots of them. They need them to cover innings and to get key outs and to add value to a roster without eating up much in terms of payroll. They are to baseball what pawns are to chess, which might not be glamorous or fair, but at least they are on the board.