Kerkering vs. Dominguez: the debate of the game

Let’s get this part out of the way. Rob Thomson’s decision to bringing in Orion Kerkering over Seranthony Dominguez in the seventh inning yesterday was not the reason the team lost. It didn’t help, which is what we’ll talk about here, but to win a baseball game, a team generally needs to score more than one run. That’s the reason right there. That’s why the Phillies lost.

But maybe they could have helped themselves with a little pitching wisdom.

The Phillies had taken the lead in the game in the seventh inning thanks to rattling the Diamondbacks bullpen, Bryce Harper scampering in from third on a wild, wild pitch from Ryan Thompson that put the game, and Arizona’s season, on the brink. It left the Phillies with a decision: who was going to pitch in that seventh inning? When the bullpen door swung open, the die had been cast. Now, based on the past in this game situation, manager Rob Thomson has usually used his relief triumvirate of Dominguez, Jose Alvarado and Craig Kimbrel in some order to shut the door on the opposition. That order can sometimes vacillate between pitchers and the inning they’re handed, but that’s generally been Thomson’s most trusted group in the bullpen. So as the bottom of the seventh commenced and Kerkering came out, the head scratching began. Why was he going away from a formula that had worked for him so often?

Thomson defended the move in his postgame comments, saying:

“We knew, in that part of the lineup, there probably were going to be some left-handers pinch-hitting,” Thomson continued. “He’s really good on left-handers.”

Ok, let’s look at that. The Diamondbacks had three right-handers coming up in Tommy Pham, Lourdes Gurriel and Evan Longoria. So right there, that tells you the team was anticipating pinch hitting occurring, an outcome that came to fruition when Pavin Smith came to the plate in the place of Longoria. Summoning Kerkering from the bullpen over Dominguez also means that Thomson and his coaching staff liked the matchup more. Digging into the numbers a bit, you can see why. According to Fangraphs, Pham, Guerriel, Longoria and Smith all present varying degrees of success against sliders, the pitch Kerkering lives and dies on at this point in his early career.

Pham: 3.0 runs above average
Gurriel: -2.2
Longoria: 0.0
Smith: -5.2

With Dominguez unable to harness his slider with the regularity he did last year lately, if that’s the kind of pitcher Thomson wanted the Diamondbacks to face, bringing in Kerkering does show some merit.

To flip the argument on the other side, we’d need to look at what Arizona does against two-seam fastball, the pitch that Dominguez has been relying on of late. During the season, Arizona has been quite bad as a team against sinkers on the year, something that Dominguez has featured on the year. Of those hitters in particular, they also struggle with the pitch as much as they do the slider.

Pham: -2.8 runs above average
Gurriel: -2.5
Longoria: -1.8
Smith: 2.9

Dominguez has also been very, very good of late. He’s yet to allow a run this postseason and if we go back to the regular season, Dominguez has only allowed one run since September 10. Are his outings a little hairy, a little dicey? Sure, but he’s gotten the job done.

I understand the desire to get Kerkering some high leverage innings and appearances. He’s got the stuff to do so, and by all accounts, the demeanor. My only quibble is: was it necessary to do so in a playoff game? Maybe this was the time Thomson thought was best. Maybe he felt his offense was going to spring to life and provide more support later in the game. Maybe he didn’t like how Dominguez or any other reliever in that situation matched up with the Diamondbacks.

Maybe he just trusted Kerkering to do better in that spot.

Whatever the reason is, Thomson did it and it would end up backfiring in the game. If you’re a believer in those numbers on a pitch by pitch basis, then it really doesn’t matter who was brought in that inning. Maybe fate had the Diamondbacks winning all along. After all, Craig Kimbrel exists. But as with any decision, we’re left to wonder what might have been had Dominguez been used that inning in place of Kerkering. Ultimately, it won’t matter if the Phillies win the series. Until they do, this will be one of those decisions to wonder about as we continue watching.