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Bullpen usage and the effect on offense

There are going to be many effects a 60 game season and shortened “summer training camp” will have on teams. Every aspect of the game is going to be approached differently when it’s a sprint to the finish instead of a 162 game marathon.

Summer training camps started last week for all 30 MLB teams and they have until July 23 (or 24th) to get their players ready for action in games that count. That isn’t a lot of time to get a pitching staff stretched out and ready to pitch in games that matter, especially with less than three weeks until the season kicks off. Many teams are still considering which pitching strategy they want to employ. Some teams, such as the Yankees, have multiple impact arms in their bullpens. The teams with superior bullpens will need to consider how long they want to push their starters in a shortened season. What effect will there be when batters have to take more at-bats against bullpen arms instead of starters?

Hitters vs. starters and hitters vs. relievers

If we look at the last three years of statistics comparing the results against starters and relief pitchers, we see a small but noticeable difference:

2017
Split PA HR/PA SO SO/PA BA OBP SLG OPS BAbip tOPS+
vs. SP 114870 0.035 23691 0.206 0.261 0.326 0.440 0.776 0.301 104
vs. RP 70425 0.030 16413 0.233 0.245 0.321 0.403 0.724 0.297 94
2018
Split PA HR/PA SO SO/PA BA OBP SLG OPS BAbip tOPS+
vs. SP 110437 0.032 23868 0.216 0.250 0.315 0.416 0.731 0.293 101
vs. RP 74702 0.028 17339 0.232 0.245 0.322 0.400 0.722 0.299 99
2019
Split PA HR/PA SO SO/PA BA OBP SLG OPS BAbip tOPS+
vs. SP 107495 0.038 23970 0.223 0.256 0.320 0.444 0.763 0.299 101
vs. RP 79022 0.035 18853 0.239 0.247 0.327 0.423 0.759 0.297 99

Across the board you can see that batters struggled more against relievers than starters. In 2019, they saw a ten-point drop-off on their batting average vs. relievers but a seven-point increase in on base percentage. That makes some sense if you subscribe to the idea that bullpen arms are in the bullpen because they could never make the jump to the rotation due to control issues (see Dellin Betances).

What will happen to offense?

In 2020, there are only going to be a handful of players teams will feel comfortable with going six innings right out of the gate. For the Yankees, I can think of three players they would probably let pitch deep into games. Gerrit Cole, James Paxton and Masahiro Tanaka. All three are established veterans that Aaron Boone trusts to give the team a quality start every time out.

The other starters, Jordan Montgomery and JA Happ, have questions marks surrounding their long-term health or performance. Other teams aren’t so lucky and have few reliable options in their rotations (see Boston Red Sox). When your starters aren’t going five innings (or even four innings), that means more innings on your bullpen.

There are some theories floating around that more bullpen games will have a negative effect on batting averages. The idea is that instead of seeing a starter for two or three times every game, you will only see him once. Baseball is a game of adjustments. Brett Gardner leads off a game against an average starter with the idea of seeing as many pitches as possible so that the rest of the team can see what they might get in their respective at-bats. If that starter is only going through the line-up once, seeing all those pitches doesn’t have the same value. I think the players are going to be relying on scouting reports before (and during) the game in order to have a better strategy from one at-bat to another within each game.

The league batting average in 2019 was .252. It’s possible that an increase in bullpen usage could push that batting average down substantially. Some of the predictions I have heard have been in the range of .230 to .240 for the league-wide batting average. That goes against some of the louder predictions we’ve heard boasting about the possibility of seeing multiple .350 hitters (and yes I include myself in that group). If we see lower batting averages than power becomes that much more important. Instead of relying on hitting with runners in scoring position, you have to get men on base and play for the three run homer.

Think of the Yankees strategy in 2011 and 2012. That’s the game plan. Then, it becomes a vicious circle because players will sell out for power which compromises their contact profiles even more.