David Phelps may not fare well as a starter

The Miami Marlins smartly converted David Phelps, long-time swingman, into a full-time relief role, and he shined with a strong first half. He made 50 relief appearances and threw 54 1/3 innings with a 2.65 ERA and 2.82 FIP. FanGraphs has this performance as the 18th-best in the majors among relievers, mostly on the back of Phelp’s workload. Those 54 1/3 innings are the 10th-highest amount of innings pitched by a relief pitcher this season.

Phelps has had great results, obviously. He is suddenly striking batters out, posting a 31.5 percent strikeout rate to go with a modest 10.1 percent walk rate on the year. His month of July was not the most impressive, as he gave up a few too many homers en route to a 3.65 ERA and 4.43 FIP, but the point stands: Phelps as a high-leverage reliever, at least in 2016, has been a success.

It would have been nice for the Fish to keep things that way, but circumstances have forced their hand. The team is out of useful starting pitchers who are ready and on the 40-man roster, and due to the team’s relative bullpen depth, they will turn to Phelps for his first start of the season on Friday night in Colorado against the Rockies. Phelps started most of last year before bowing out in August due to injury, and he posted a respectable but ultimately unimpressive 4.50 ERA and 4.03 FIP.

Can Phelps take what he has done in the bullpen into his work as a starter? What has changed between last year and this year?

Velocity Gains

The biggest and most obvious change is the pickup in speed from all of Phelps’s offerings. He has gained a whopping three miles per hour on his fastballs and two mph on his cutter, his two primary offerings. The curveball has picked up a small amount of speed, but the biggest differences have been on his primary pitches. As we know, velocity can play a big role in the effectiveness of a pitcher’s pitches; all other things equal, you want your fastball at a higher velocity, because that makes it harder to hit. Every mile per hour gain is worth approximately a third of a run in terms of ERA.

Why did Phelps gain that velocity? It should be clear that the reason is the move to the bullpen on a permanent basis. Before that, Phelps pitched in either a swingman role in which he had to be stretched out for multiple innings or as a starter. After a short time period this year, Phelps was established as “the eighth inning guy” for manager Don Mattingly and the Marlins, and that knowledge of his role allowed him to exert extra effort.

At the same time, it is not as though Phelps has never worked out of the pen before. He spent all of April in 2014 working out of the bullpen with the New York Yankees. At the time, he was still working as a swingman, but it was still a known bullpen role. In that month, he was averaging only 91.7 mph on his fastball, much like what he did last year as a starter. It does not seem likely that all of the velocity gain is from moving to the pen, and it is possible he will keep some of it starting tomorrow night, even if it probably is not all of the gains of this year.

Whiffs in the Wrong Places

Remember earlier in the year, when we talked about how Phelps has been successful this year? The two reasons remain the same: velocity and his odd swinging strike rates on pitches in the strike zone. Phelps is missing bats out of the strike zone as well, but at league average rates. What has set him apart is his 81 percent contact rate on pitches inside the strike zone, which ranks 31st in all of baseball among the lowest contact rates among relievers. Among the 30 guys with lower in-zone contact rates, only one player (Justin Miller) had a higher rate of contact on out-of-zone pitches.

Players who post low in-zone contact rates are usually guys who miss bats well with fantastic stuff, and those players tend to have swinging strikes on pitches out of the zone at fairly frequent rates. Phelps has done this in a different fashion, opting to pound the strike zone and hope that hitters miss. Hitters are not chasing after a lot of Phelp’s pitches; he owns the second-lowest rate of swings on out-of-zone pitches. This is the exact same thing he did last season as a starter as well, except with higher contact rates.

Phelps did not seemingly add a new pitch to his repertoire. He instead took out his changeup and decreased his curve usage, depending on two types of fastballs and his cutter instead. Last year, as a starter, none of those three pitches broke a 20 percent whiff rate, nor did his curveball. This season, his fastball, cutter, and curve are each being missed on at least a fifth of their swings with nothing seemingly changed but their velocity.

The pitches do not have some new break to them. They are locating in the same areas as they were last year. The only difference this season is velocity, and that change may be less prominent once Phelps returns to the rotation. There are question marks as to whether there is any potential success waiting for him in a move up to a starting role, and it all hinges on that velocity. It may be at this stage the only thing maintaining his strikeout rates, and without it he may go back to being the unassuming back-rotation guy he was all those years with New York. There may be more value to him working in the mid-90’s as a reliever at that point. We all await to see the results on that first fastball.