Joe Musgrove Is Sneaky Good

Even if the team isn’t quite a contender, there are plenty of reasons to follow the 2020 Pittsburgh Pirates. Bryan Reynolds and Josh Bell are interesting hitters, though there’s a decent chance that neither ever replicates their 2019 success. Chris Archer is a fun puzzle; can he regain the scintillating form he flashed at times on the Rays, or will he be more 2019 Chris Archer, all homers and walks? Mitch Keller is awesome, except when he’s terrible. Those are all storylines you can follow as a Pirates fan. Me? I’m going to be watching Joe Musgrove.

Musgrove put together a nice season in 2019, his second straight year of more than 100 innings and more than 2 WAR. That sounds great, but it’s a little less impressive under the hood. His RA9-WAR has been significantly lower, and if you’re more of an underlying skill person than a runs allowed type, his above-average FIP’s have been misleading; they’re largely down to his suppression of home runs, and if that skill fades, his results might start to look more like his xFIP:

I’ll admit I’m not doing a good job of explaining my fascination with Musgrove so far. Even if you dig into the component parts of his game, nothing jumps off the page. He strikes out fewer batters than average but makes up for it by walking even fewer. He allows a roughly average number of grounders, gives up hard contact at a roughly average rate, and overall blends into the background.

But wait! If you only care about the most recent start that every pitcher has made, Musgrove looks awesome! On September 26th, he went six strong innings against the Cubs, striking out eight while walking only two. He did allow two earned runs, but that was largely due to a horrid 40% strand rate. His FIP (1.55) and xFIP (2.87) were both spectacular.

Heck, zoom out to the other two starts Musgrove made in September (he skipped a turn due to discomfort in his foot), and it’s still dominance city: he struck out 32.8% of the batters he faced en route to a 1.34 FIP and 2.58 FIP. Heck, even if ERA is your jam, it was 2.25. Musgrove looked, if only for a moment, like Jacob deGrom (31.7% strikeout rate, 2.43 ERA, 2.67 FIP in 2019).

If I could offer you one piece of advice about looking at statistics, it would be not to do what I’m doing here. Slice data up into small samples and you can find whatever you’re looking for. Start with the competition — those last three starts were against the Giants, Mariners, and Cubs, and the Cubs hardly ran out a full roster. That might help any pitcher.

Even without the issue of competition, the sample is simply too small. Mike Leake was quite poor last year — he had the highest FIP among qualifying pitchers and ran a career-low strikeout rate. Arbitrarily look only at his July 3rd start against St. Louis, however, and he’s a house; seven strikeouts and no walks in 7.2 scoreless innings.

The reverse is true as well. I just got done making some preposterous Musgrove/deGrom comparison, but deGrom himself was bad for an entire month last year; in May, he somehow struck out only 22.4% of the batters he faced en route to a 3.83 xFIP. No one would argue that that’s his true talent level, so why am I more or less doing that in Musgrove’s case?

There are several reasons, only one of which is that it’s the middle of February and I’m looking for topics to write about. There’s the recency, for one: I was cherry-picking examples with Leake and deGrom, but with Musgrove, it’s his latest performance. That’s not sufficient, of course. Tim Hill, a Royals reliever, put together an even crazier September, with a 35.7% strikeout rate that dwarfed his pre-September 20%.

But in Musgrove’s case, there’s something more. In 28 starts before September, he averaged 92.5 mph on his four-seam fastball, and the pitch got absolutely tattooed. He barely missed any bats and batters did damage when they connected. In his three September starts, Musgrove averaged 94.5 mph on his fastball, the largest increase among all starters (excluding Jonathan Loaisiga, who faced seven batters in a single one-inning start).

What did those extra two miles an hour do? They turned his fastball from just-get-by to salt-the-earth. Batters missed on roughly 13% of their swings at Musgrove four-seamers before September. With the added velocity, that number more than doubled to 26.9%. If he’d done that over a full season, it would have been a top-20 rate among all starters, roughly in line with deGrom, which is nice company to keep.

More of a graphical learner? Well, Musgrove did this:

It’s not always as easy as throwing harder and getting whiffs. There are plenty of pitchers who throw hard without missing bats, and plenty of pitchers who rack up strikeouts without imposing speed. For Musgrove, however, it is that easy. Take a look at how often he misses bats when throwing his four-seamer a given speed over his entire career:

First, what an impressive range of velocities! Being a swingman who occasionally pitches in short-stint relief will do that. But more importantly, aside from a little noise around the extremes, the pattern is pretty clear. When Musgrove starts popping 94 or 95, batters start missing. It’s not that simple, of course, but it’s not all that complex either. Throw harder, miss more bats.

Take that into account, and Musgrove starts to look a lot more interesting. You still can’t take his 2019 stats and extrapolate them out, of course; his 0.0% HR/FB rate in September is probably not a great estimate of how he should do going forward. But the strikeouts, driven largely by his fastball missing bats at a much higher rate, look much more realistic.

For his career, Musgrove has a strikeout rate more than 2% higher when he averages above 94 mph for an appearance than when he averages below. That number would be even higher if we ignored a brief, Ray Searage-induced flirtation with heavy sinker usage in 2018 that led to games like his July 24 outing against the Indians, in which he threw 32% sinkers (at 92.4 mph) rather than lean on his four-seamer (which averaged 94.4 mph that day.)

But we don’t have to throw out those games to believe in Musgrove, because even with them in the fold (he struck out only two of the 27 batters he faced that day), harder four-seamers mean more strikeouts. And with a new coaching staff in town, it’s a safe bet that we won’t see as many trips to sinker-town this year.

Is Joe Musgrove the best pitcher in the National League? Most certainly not. But his late-season performance drives home a point that has always been there — when Musgrove throws hard, success follows. Keep an eye on him in spring training and through the first few starts of the season. If his velocity is up, there might be a new ace in town.