Pitching Performance of Position Players

As some of you may already know, I am a critical, die-hard Tigers fan. In three of their last four games, a position player has taken the mound. On Wednesday night, after Kenta Maeda left the game two pitches in due to injury, four Detroit relievers (Joey Wentz, Mason Englert, Will Vest, and Andrew Chafin) combined to throw 172 pitches, recording 22 outs. Utility man Zach McKinstry was tasked with finishing the eighth inning. He threw four sub-50 mph curveballs, getting two consecutive batters out. In their next game, the Tigers called upon Zach McKinstry, again. Reese Olson had gotten rocked to the tune of eight runs, and down ten to nothing in the ninth inning, A.J. Hinch did not want to burn another reliever. It turns out that McKinstry would retire the side in order. Two days later, in the final game of the series, Jake Bauers pitch the eighth inning for the Brewers. He walked the leadoff man but then got three outs in a row, meaning that in these three instances of position players pitching, no runs were scored. This made me curious about how offenses typically fare against position players. How unusual is this three game sample?

To this point in the season, a position player has assumed the opposite role 32 times.

Cases where at least one inning was covered…

• 3/31: Tyler Fitzgerald (SF) vs SD- 1 run in 1 IP (+1 change in scoring margin through end of game for winning team)
• 4/1: Isiah Kiner-Falefa (TOR) vs HOU- 0 runs in 1 IP (0)
• 4/3: Josh Rojas (SEA) vs CLE- 0 runs in 1 IP (0)
• 4/7: Josh Rojas (SEA) vs MIL- 2 runs in 1 IP (0)
• 4/11: Luis Guillorme (ATL) vs NYM- 4 runs in 1 IP (+4); Grae Kessinger (HOU) vs KC- 0 runs in 1 IP (0)
• 4/13: Ben Rortvedt (TB) vs SF- 1 run in 2 IP (0)
• 4/19: Tyler Fitzgerald (SF) vs AZ- 2 runs in 1 IP (+2)
• 4/26: Isiah Kiner-Falefa (TOR) vs LAD- 1 run in 1 IP (+1)
• 4/27: Matt Mervis and Patrick Wisdom (CHC) vs BOS and Pablo Reyes (BOS) vs CHC- 6 runs in 0.2 IP and 0 runs in 0.1 IP and 0 runs in 1 IP (+6); Owen Miller (MIL) vs NYY and Jose Trevino (NYY) vs MIL- 4 runs in 2 IP and 2 runs in 1 IP (+2); Aaron Hicks (LAA) vs MIN- 2 runs in 1 IP (+2);
• 4/28: Jake Bauers (MIL) vs NYY- 0 runs in 1 IP (0)
• 5/4: Emmanuel Rivera (MIA) vs OAK- 4 runs in 1 IP (+3); Tyler Fitzgerald (SF) vs PHI- 0 runs in 1 IP (0)
• 5/18: Willi Castro (MIN) vs CLE- 0 runs in 1 IP (-4)
• 5/19: Luke Williams (ATL) vs SD- 0 runs in 1 IP (-1)
• 5/31: Nick Loftin (KC) vs SD- 0 runs in 1 IP (-5)
• 6/1: Cole Tucker (LAA) vs SEA- 0 runs in 1 IP (0)
• 6/6: Danny Mendick (CWS) vs BOS- 0 runs in 1 IP (0)
• 6/7: Zach McKinstry (DET) vs MIL- 0 runs in 1 IP (0)
• 6/8: Pavin Smith (AZ) vs SD- 0 runs in 1 IP (0); Emmanuel Rivera (MIA) vs CLE- 0 runs in 1 IP (0)
• 6/9: Jake Bauers (MIL) vs DET- 0 runs in 1 IP (0)

The last nine position players to pitch an inning have combined for nine scoreless innings! Of course, this does not mean position players are pitching great. It is very likely the case that both teams simply want the game to end. The winning team does not have a collective incentive to score more runs and win by, say, ten runs rather than eight runs.

Summarizing the 24 instances where a team had position players work an inning…

observed probability of scoring x runs

• 0 – 0.625
• 1 – 0.083
• 2 – 0.167
• 3 – 0
• 4 – 0.083
• 5 – 0
• 6 – 0.042
• > 0 – 0.375

Summarizing the 23 games above where position players worked (at least) an inning…

observed probability of x change in scoring margin for winning team

• -5 – 0.043
• -4 – 0.043
• -3 – 0
• -2 – 0
• -1 – 0.043
• 0 – 0.522
• +1 – 0.087
• +2 – 0.130
• +3 – 0.043
• +4 – 0.043
• +5 – 0
• +6 – 0.043
• < 0 – 0.130
• 0 – 0.522
• > 0 – 0.348

In 2024, offenses have a .433 wOBA versus position players. To put that in perspective, Juan Soto has a .437 wOBA. Basically, hitters perform at Juan Soto’s level when a position player is throwing.

In Zach McKinstry’s outing on 6/5, he only got two outs, but he got three in his following appearance and so did Jake Bauers. If a team has a five-in-eight chance of not scoring in an inning against a position player, the probability of three straight games with no runs would be around 0.25. Not such a rare streak after all.