A popular topic of conversation right now in Yankeeland is Vidal Nuno's spot in the rotation and whether or not he deserves to keep it. He did little to help his cause last Saturday when he gave up 3 home runs in a loss to Baltimore, his 11th, 12th, and 13th in 12 starts, and I think Joe would like to remove him if he could. Unfortunately for him, the organizational starting depth being stretched thin by injuries has left the Yankees without a suitable replacement sitting front and center.
One name that's been talked about a lot as a possibility is Adam Warren. The former starting pitching prospect has settled nicely into a middle relief and occasional setup role this season after being given a token spot in the Spring Training 5th starter competition. Warren made the transition from starter to reliever almost full-time last year when he earned himself a bullpen spot out of spring camp, and while he hasn't worked as a starter since 2012 it's reasonable to think he could be at least a slight improvement over Nuno. The question of swapping Nuno for Warren has been brought up to Joe plenty in the last week and he's admitted that it's something he's considering. The real question is whether it's the right move to make.
Warren has been a revelation in the 'pen this year for Joe and the Yankees. As a guy who worked almost exclusively in lower-leverage middle and long relief innings last season, Warren was basically average with a 3.39/4.32/3.98 slash line, 19.3% K rate, and 9.1% BB rate in 77.0 IP. This season he's improved across the board, pitching to a 2.88/2.62/3.12 line that includes his bombshell of a last outing (4 ER in 1 inning), 23.5% K rate, and 6.6% BB rate in 40.2 IP. Along with Dellin Betances, he's become a part of Joe's trusted bullpen inner circle, getting the call time and time again in close games and big situations. You could make the argument that Warren has been one of the 4 or 5 most valuable Yankees through 75 games.
So how would he do as a starter? His past history suggests that he might not be as clear cut an improvement over Nuno as it seems, and I'm not just talking about the 8 ER and 5 BB he's allowed in his 3 career Major League starts (10.1 IP). Go back to Warren's days at Triple-A and you won't see a lot that jumps off the board about his game. In 300+ IP at the level from 2011 to 2012, Warren had a K rate in the mid-teens, a BB rate in the mid-7s, and a FIP in the high 3s. Decent enough numbers, but ones that were typical of a pitcher who didn't have big stuff and predictive of a ceiling as a 4-5 starter. Warren's shaky displays in his few Major League starts, on short notice or not, combined with his boring Triple-A results gave some indication to the Yankee decision makers that he might not be more than a Quad-A type as a starter. Unfair SSS bias or not, that surely factored into their decision to make him a reliever.
The move to the bullpen has brought with it the bump up in stuff that most converted starters experience, and this year Warren has really started to harness that stuff. His fastballs that used to live 88-92 are all averaging over 93 MPH this season, including 94.1 on his 4-seamer. He's also added a little zip to his curveball and a few ticks to his changeup, which has become a much more important pitch for him. Warren's altered his pitch mix to feature fewer fastballs and more sliders and changeups this season, a transition that started last year when he first moved to the 'pen and one he appears to be figuring out this year.
The tweaks to his approach and boost to his velocity have made Warren a better pitcher and given him the swing-and-miss stuff he lacked as a starter. The positive results from those changes have to help build confidence, and Warren admitted last week that he's had a change in mindset and how he goes about his job now that he's settled into a relief role and had success in it. How well would he do scrapping his new approach and going back to a starter's mentality? How would his stuff hold up over 6 innings compared to 1 or 2 and how successful would he be facing hitters 2 and 3 times? Is there anything he can take from his relief experience that can make him a more effective starter?
Those are all the unknowns that make the decision to replace Nuno with Warren such a tough one, to say nothing of the gaping middle relief hole that would be left if Warren was moved into the rotation. Shawn Kelley hasn't exactly come back strong from his month-long DL stint, Joe is making much more of an effort to limit Betances' workload, and nobody in the lower half of the current 'pen can be trusted with important innings in close games. Warren is a critical piece in the bullpen and his presence there as a reliever capable of going out and pitching multiple innings if needed in support of someone like Nuno or Phelps or Whitley is probably more valuable than him pitching at a level comparable to Nuno's as a starter.
Which is not to imply that I think Warren would be that bad as a starter. In fairness to the guy, I'm going on MiL stats and a handful of Major League starts here, which is hardly accurate support for any definitive statements about his potential as a starting pitcher. But with the success he's found as a reliever, the changes he's made to how he goes about the game, and the time that would be needed to stretch him out in the Minors before making the swap, I don't think the net gain from the move would be all that great. The Yankees' recent history of shuttling their young pitchers between starter and reliever roles isn't one that's filled with a lot of success stories, so for the time being I'd rather see them continue to ride it out with Nuno and keep Warren where he's at.