Does Matt Cain or Jake Peavy move to the bullpen?

Edit: Well, shoot.

Jake Peavy is going to the bullpen.

— Andrew Baggarly (@extrabaggs) August 2, 2016

Still, it was an interesting thought exercise!

This will be a simple thought exercise, a short post. Probably. The Giants have a new starting pitcher. He throws 94 mph, he’s young, and they just gave up sweet, sweet Matt Duffy for him. Matt Moore will be in the rotation.

So will Madison Bumgarner and Johnny Cueto. And probably Jeff Samardzija, even if he’s the only member of the rotation with extensive bullpen experience. He’s too expensive, too vital to the future of the organization to mess around with. That leaves Matt Cain and Jake Peavy as the pitchers who are most likely to lose their role.

Well, which starter goes?

Start by figuring out which one has had more success in the rotation recently. That would be Peavy, and it’s not especially close. Peavy was good last year — not whatever-fine-I-guess, but good. He had an ERA+ that was better than the league average, and he was about a win or two better than replacement. Now that he’s overcome a start to the season that looked like it had a chance to be career threatening, it’s easier to remember that.

Cain hasn’t been average or better since 2012, which is a long time ago in pitcher years. We can do some statistical gymnastics to explain away Peavy’s 5.47 ERA this season — that a disproportionate number of the runs were concentrated in a couple nightmare outings, that his FIP suggests he’s been unlucky — but that ERA is still lower than anything Cain has done since 2014.

Then move on to which pitcher fits a relief profile better. Matt Cain averages 90.2 mph with his fastball, with a max of 92.8. Jake Peavy averages 85 mph on his cutter and 88.8 mph on his fastball, with an equal mix between the two, but he’s topped out at just 91 mph. Now while fastball velocity isn’t the only way to measure a reliever’s effectiveness, there’s always a hope that a starter will pick up a little velocity after he’s converted. That extra velocity would bring Cain a lot closer to the average reliever than it would for Peavy, who has always been more about location and movement than velocity.

The stats are compelling, too. Here’s how Matt Cain has progressed in his starts this year:

Last year? Same thing. These are smaller samples, but the trend has held true throughout his career. Matt Cain has always been more effective in his first 25 pitches.

As for Jake Peavy, he’s been a little better with his first 25 pitches this year, but the split isn’t so dramatic. And last year he was at his best in the middle of his starts, dramatically so, and that’s been the case for most of his career, too.

There’s a danger in paying attention to microsplits like that, sure, but match it with your anecdotal evidence, then. Which pitcher would you trust more to adopt a leave-it-all-out approach to pitching a single inning?

Neither. They’re both gonna allow a million home runs.

Be nice. The answer to the question is Cain, who pitches off the fastball more. Really, the only argument I can come up with for sticking with Cain is that he’s under contract for next season, when the Giants will still need a starter. The counterargument to that would be that they’ll also need a reliever, and the starting gig hasn’t worked out for Cain’s last four seasons. This might be giving him a chance to succeed, not taking one away.

I’m willing to listen to arguments to the contrary, but I can’t find a good one. Hard to find even a passable one, really. Peavy’s been the more successful starter. Cain would benefit more from a quicker fastball. Cain’s problem has been getting outs in the middle innings.

[bangs gavel]

Alright, we solved it. Cain’s in the bullpen, where he’ll be eased into higher-leverage roles as his performance dictates.

Have enough time left over to make lunch, this is great. All takes should be this quick and easy.