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The Red Sox hope Nathan Eovaldi is finally reaching his potential

Nathan Eovaldi might have the highest upside of any starter that was available on the market. The problem is his ability to reach it.

Tampa Bay Rays v New York Yankees Photo by Mike Stobe/Getty Images

By trading Jalen Beeks for Nathan Eovaldi, the Red Sox are banking on the adjustments that Eovaldi has made since returning from Tommy John. Eovaldi has always had great stuff—a fastball that sits in the high 90s as well as a slider with two-plane movement—but he hasn’t been able to put it together in his last few healthy seasons. Though his FIP suggested he should have been nearly a run better in 2015 and 2016, he’s always shown a propensity to give up hard contact.

Eovaldi is set to make his first start for the Red Sox on Sunday against the Twins. He’ll be taking the slot of Brian Johnson who is starting once more on Thursday before moving back to the bullpen according to Zachary Silver of Johnson moved into the rotation after Steven Wright went on the disabled list with knee inflammation.

When Eduardo Rodriguez returns from the disabled list, Drew Pomeranz will likely be the odd man out. In 41.2 innings, he’s put up a 6.91 ERA and 5.70 FIP behind a 8.7 K-BB%.

Out of all the pitchers on the market, Eovaldi might have the most upside. The Red Sox picked up because they’re hoping he can reach his full potential with them. His first few outings after returning from injury were promising. Jeff Sullivan at Fangraphs wrote about the adjustments Eovaldi had made.

Reduced fastball usage. Increased cutter usage. Increased fastball height. Improved fastball-cutter tunneling. Eovaldi still throws his slider, splitter, and occasional curve, but the big changes have been with the primary two pitches, and in so many ways he comes off as something of an analytical success story.

Eovaldi is one of the many pitchers moving away from the fastball, and it has been effective for him at times. Even in limited time, his fastball has been worth more runs, 3.2, than it has since 2013. In three of his ten outings this season, he’s thrown at least six innings without giving up a run.

He’s also had as many starts where he’s given up at least four runs. His ERA and FIP are 4.26 and 4.28 respectively despite a 3.6 percent walk rate. Almost as if to spite Sullivan, Eovaldi gave up eight runs in 2 23 innings in his first start after that article was published. In that outing, the Twins did most of their damage against his fastball and cutter often jumping on pitches early in the at-bat.

As Sullivan pointed out, when he can tunnel his cutter and fastball together, it becomes a devastating combination. He can survive with cutters middle-middle because when he can throw it in a similar spot as his fastball, hitters aren’t expecting the pitch to break. When he can’t, it doesn’t fool hitters.

Baseball Prospectus

In this pair, Eovaldi threw Brian Dozier a fastball down and backed it up with a cutter over the heart of the plate. It would up being a fly ball caught at the warning track, but Dozier took a balanced swing and it might have been gone in other parks. Eovaldi did Dozier a favor by elevating the pitch and slowing it down. The fastball and cutter work best when the sequencing is reversed. It should follow the same principle as throwing a changeup down followed by a fastball at the letters. The high velocity on his fastball allows him to use his cutter like a changeup.

When he throws his fastball in the strike zone, it needs to stay in the upper third because that’s where hitters are most likely to swing and miss at it. If not, he needs to keep it at or below the knees. It’s when he keeps it in the lower two-thirds that he gets into trouble.

Brooks Baseball

Eovaldi gives the Red Sox a glut of options in October and a back-up plan in case Rodriguez has a setback or another starter goes down with an injury. A team can’t have too much starting pitching depth especially when their fourth or fifth starter has as high a ceiling as Eovaldi. The issue is hitting that ceiling. In 2018, Eovaldi has shown that the adjustments he’s made can work. It’s just a matter of him executing his pitches and sticking to the plan.

Kenny Kelly is a writer for Beyond the Box Score, McCovey Chronicles, and BP Wrigleyville. You can follow him on Twitter @KennyKellyWords.