At this time last year, Justin Slaten was pitching for the Frisco RoughRiders, the Texas Rangers’ Double-A affiliate.
Now he’s statistically one of the top relievers in the majors.
The Red Sox’ Rule 5 rookie is tied for sixth among qualified major league relievers in Fangraphs WAR (1.2).
“Honestly, it’s not something I even was aware of,” Slaten said when told he’s sixth on the list. “I try not to really think about stats and stuff like that. I’m really just trying to quantify my outings as if I did my job or if I didn’t. I feel like I’ve had some games that I’ve pitched in that have been high leverage and I’m very thankful for that. I don’t really know what goes into quantifying WAR.”
Red Sox reliever Justin Slaten pitched a scoreless ninth inning Friday against the Yankees.
It’s not just WAR though. Slaten’s Baseball Savant page is very red.
The 26-year-old — who threw a perfect six-pitch ninth inning in his first ever game at Yankee Stadium on Friday — is in the 97th percentile in chase percentage (35.9%), 94th percentile in barrel percentage (3.5%), 91st percentile in walk percentage (4.8%) and 86th percentile in both expected ERA (30.5) and whiff percentage (30.5%). He’s also in the 85th percentile in fastball velocity (96.2 mph) and average exit velocity (87.1 mph).
MassLive showed Slaten his Baseball Savant percentile rankings and asked him his favorite stat. He chose whiff percentage.
“I think it feels good when you throw a pitch and they swing and miss,” Slaten said. “To me, it’s like you fooled them. It’s not like an ego thing. Well, I guess it kind of is because you think about it — if you’re out there throwing, I’d much rather get a swinging strikeout than a looking strikeout just because it feels good. You throw a pitch and you beat a guy, it feels good. Just like it feels for a hitter whenever they’re on (a pitch) and they hit a home run. It’s the same way. I’d say that’s kind of like the home run of pitching is like when you’re going out there and you’re throwing and you’re missing bats. That’s the best feeling.”
Slaten has had one of the better four-seam fastballs this year. Opponents are batting just .147 (5-for-34, all singles) with a .147 slugging percentage against it. He throws the four-seamer 27.1% of the time while throwing his cutter 38.9% and his sweeper 27.9%.
“I feel like recently it hasn’t felt that good,” Slaten said about his fastball. “I’ve been kind of struggling with the command of it recently. And so I think that’s kind of been a thing that’s led to some of my recent struggles. Just not being able to put that in the zone as much. But I know that when I’m throwing it where I want to throw it and letting all of my other stuff play off of that, that that’s when I’m at my best.
“So like (Friday) night, being able to come in and drive some fastballs into the zone and be able to throw the cutter off of that,” he added. “And just trying to keep guys off balance because I feel like both of those pitches, they kind of come out the same. So for me, if I can be in the bullpen (warming) and know that I’m really dialed in with the fastball, that’s what’s going to be the main separator for me out there. It doesn’t matter how good the other pitches are. If I can’t throw the fastball in the zone, then I’m going to have a hard time because they (hitters) are just able to eliminate what is probably my best pitch statistically.”
