Jameson Taillon joins the Pirates' rotation today, and despite Neal Huntington's protests to the contrary, he seems likely to stay. That means someone needs to go, and the widely held assumption is that Juan Nicasio will move to the bullpen. That might happen, but I'm not sure it should.
Nicasio is a frustrating starter. He throws two pitches about 95 percent of the time, which makes him vulnerable against lefties and over long stretches.
Still, he hasn't been bad. Including last night's strong performance, he's whiffed a batter per inning this season while walking a very reasonable 3.6 batters per nine. His ERA is 4.50, but xFIP and SIERA mark him as something closer to 4.00 for the season. Good velocity, plenty of strikeouts, and reasonable control -- I'll take that from a starter, even if it comes with obvious downsides.
So if Nicasio stays in the rotation, who goes? The Pirates' worst starter this season has been Francisco Liriano, but he won't, and shouldn't, come out of the rotation if he's healthy -- the Bucs need Liriano to return to his previous form. Gerrit Cole is Gerrit Cole, and Jon Niese has been better lately. That leaves Jeff Locke.
Nicasio has been markedly better than Locke, Locke's decent results lately notwithstanding. Locke has a 4.28 ERA and a 47.9 percent ground ball rate, but those are about the only respects in which he's been better than Nicasio. Locke's strikeout rate, never particularly strong, has dipped to an untenable 4.7 batters per nine innings this year. That hasn't improved in his last several starts, in which he's gotten good results -- Locke has allowed just seven runs over his last three starts, spanning 22.1 innings, but he's struck out four batters total. That's not a marker of sustainable success, so Locke's recent solid-looking performances don't mean he's actually improved.
In fact, advanced stats suggest Locke has actually gotten worse this season. His xFIP is currently around five, about a run higher than Nicasio's, and his SIERA is even higher. Projection systems, too, are higher on Nicasio. Here are ZiPS and Steamer's rest-of-season ERA projections:
I've focused on 2016 stats here, and this could just be fun with small samples, but we basically know what we're going to get from each pitcher. I'll take the guy who strikes batters out, not the guy who perpetually nibbles and who seems to be heading backwards despite never having established himself as more than a back-of-the-rotation starter in his fourth full year in the league. Nicasio has upside. Locke does not. I've tepidly defended Locke in the past, but at this point, the Pirates can do better. The Bucs should, in my opinion, move him to the bullpen to see if he can add a few miles an hour and reclaim some value in a long relief role.
It's true that, when one looks at Nicasio, one sees a reliever. In fact, one of the better arguments in favor of bumping Nicasio to the bullpen is that the value he would add there is much greater than the value Locke would add. That's hard to argue -- Nicasio's power two-pitch repertoire seems ideally suited to relief. Maybe Locke would experience a velocity bump if he pitched out of the 'pen, but it's hard to see him as, say, a good setup man, and easy to imagine Nicasio being one.
Another argument in Locke's favor is that he works deeper in games than Nicasio -- Locke has averaged 6.12 innings per start this season, while Nicasio has averaged 5.27. The Pirates will get more innings from Jeff Locke in the rotation.
The flip side of that argument, though, is that the Pirates will get more innings from Jeff Locke in the rotation. If Locke sticks as a starter for the rest of the season (perhaps unlikely given the quality of Indianapolis' starters, but stick with me for a second), he might pitch about 100 more innings, versus the 50 or so Nicasio will pitch if he moves to the bullpen. Even granting that Nicasio will pitch higher-leverage innings out of the bullpen, wouldn't it be better to give those 50 (or maybe 45) extra innings to the superior pitcher? Locke as a starter will probably give the Pirates more innings than Nicasio as a starter, but the quality of Locke's innings has been so poor that I'm not sure that matters.
Nicasio is only a decent fit as a starter and an excellent fit as a reliever. But he should continue to start, at least until more reinforcements arrive from Indianapolis or in a trade.