David Phelps is Ready to Break Out if the Marlins Let Him

There are plenty of ways to characterize David Phelps‘ success in 2016. Among pitchers who threw at least 80 innings, he posted the 5th-best ERA (2.28), 6th-best xFIP (3.15) and 7th-best FIP (2.80). That’s a big deal, although it’s a decidedly smaller deal considering the bulk of Phelps’ innings came from the bullpen.

The reason for Phelps’ success — the cause to the effect, that is — is fairly obvious:


Phelps added more than 3 mph to his four-seamer and sinker as well as a tick or two to each of his off-speed pitches.* In an August edition of his NERD game scores, Carson Cistulli quipped, “As with most other pitchers, Phelps at 94-95 [mph] is markedly different than Phelps at 91.” Indeed, Cistulli. Phelps looked like a changed man.

It’s easy to attribute his sudden late-career success to his almost-full-time move to the bullpen. It’s how the narrative typically plays out: a pitcher’s velocity plays up better in short spurts. It’s why we expect failed starters can become elite relievers. It’s a cognitive bias, but it’s a bias we have because it tends to be true. This shorthanded logic, however, undersells Phelps’ gains both under the hood and on the mound.

It was the perfect test of the null hypothesis: deploy Phelps in the rotation for an extended period of time. In the month of August, Phelps appeared in games exclusively as a starter, leaving and returning to the bullpen on July 30 and Sept. 12, respectively. He didn’t once step out of a bullpen in August. And his velocity? It stuck.


Phelps sustained his velocity as a starter (although I acknowledge he wasn’t forced to bear the burden of a starter’s workload). And he demonstrated that he could be just as, if not more, successful in a starting role, notching identical rates of strikeouts per nine innings (11.84 K/9) and weighed on-base averages against (.256 wOBA) as well as a better strikeout-to-walk differential (22.5 K-BB% to 21.3%) and xFIP (2.97 to 3.22).

Granted, it’s a small sample, but Phelps was essentially a 5-WAR pitcher in his August rotation stint, and he was a 4-WAR pitcher when prorating his 87-ish innings to a full 200. Should he come even remotely close to replicating his 2016 season, he would easily be the Marlins’ best starter.

Unfortunately, the Marlins apparently have no interest in finding out if this golden ticket will actually let them into the chocolate factory. Michael Hill, president of baseball operations for Miami, told the South Florida Sun-Sentinel in December he’d keep Phelps in the bullpen if he had his way. Accordingly, FanGraphs has projected Phelps for only 19 innings as a starter, instead allocating starts to Justin Nicolino and his projected 4.9 K/9 (ugh).

Just know that all of Phelps’ pitches benefited from the added velocity, registering whiffs on swings about 50 percent more often across the board. His sinker and curve induce ground balls at elite rates and didn’t allow a single home run in 2016. His walk rate leaves much to be desired, but pitchers with big strikeout rates, such as Tyson Ross and Lance McCullers, make due with unsightly walk rates (although it’s worth noting those two induce better ground ball rates, too). He has his flaws, but he has four legitimate offerings that now all play up with velocity, regardless of his role. Obviously, he’s no guarantee to succeed. Walking four hitters per nine innings is something like walking a tightrope in this day and age. But what do the Marlins really have to lose?

Perhaps the Marlins will see the error of their ways. And the inevitability of poor performance (from any of Miami’s mediocre starters) and injury (ditto) could open the door for him to re-enter the rotation. Until then, it’s hard to rely on Phelps for much of anything, really. He could be one of those highly effectively middle relief arms, but his expected role effectively caps his upside.

Phelps is a name to remember in deep leagues and dynasty formats, even if he’s 30 years old. He’s being drafted outside the top 400 in National Fantasy Baseball Championship (NFBC) drafts, establishing a potential return on investment that’s very difficult for me — and, I encourage, also you — to ignore.

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*Does anyone know anything about Phelps’ offseason regimen? Any indication of what might’ve manifested his velocity bump? I scoured the internet (aka I searched Google for, like, eight minutes) and couldn’t find anything. Any information is appreciated!

Currently investigating the relationship between pitcher effectiveness and beard density. Two-time FSWA award winner, including 2018 Baseball Writer of the Year, and 8-time award finalist. Featured in Lindy's magazine (2018, 2019), Rotowire magazine (2021), and Baseball Prospectus (2022). Tout Wars competitor. Biased toward a nicely rolled baseball pant.

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5 years ago

OK, I was watching a Marlins’ game last season when Phelps was pitching (yes, I live in Florida), and I believe the announcers said that throwing harder was simply a function of being a reliever, of not having to pace himself. So that after his success as a reliever his coaches told him to keep throwing hard, even when starting.

Lunch Anglemember
5 years ago
Reply to  Jim

Reminds me of Hector Santiago. His velocity increased a couple notches at the beginning of this year and I heard the a similar story, that he just decided to throw harder every pitch instead of pacing himself. His velocity declined later in the summer though. Keeping it up is difficult, it turns out.

5 years ago
Reply to  Jim

Also, Carrasco