Starting Pitcher GB% Surgers — Apr 21, 2021

Over the last two days, I identified and discussed the hitters whose FB% has surged and those whose FB% has declined versus 2020. Today, let’s move over to starting pitchers. Unlike for hitters where depending on the type of hitter they are, the optimal batted ball profile is easier to determine, it’s not as straightforward for pitchers. So this isn’t necessarily a “good” list to be on, but it could change the shape of the pitcher’s performance. More grounders should result in fewer homers, but likely more hits allowed and a higher BABIP. So let’s get to the names of those that have increased their GB% by at least 10%. Of course, remember we remain well into small sample size territory.

It’s two small samples we’re comparing from Casey Mize, but if you also include his minor league rates, it’s clear this is a big jump in GB%. However, this isn’t totally real. His FB% is only slightly lower than his historical marks, so rather than trading flies for grounders, he has traded line drives for grounders. That’s good! But, it’s not sustainable, as suppressing liners isn’t really a skill a pitcher suddenly learns. It’s far more noisy than ground ball and fly ball rates, so expect Mize’s batted ball distribution to revert closer to his historical levels. Of course, his pitch mix has changed (plus a velocity spike), and he has induced tons of grounders with his slider and splitter, so perhaps he does finish with a higher GB% than historic marks. That said, I wouldn’t expect it to remain this high.

Steven Matz sits second on the list, but it’s deceiving. He’s coming off his lowest GB% of his career, as previous grounders became line drives, which resulted in a bloated .341 BABIP. This season, his batted ball distribution is right back in line with his career averages. His luck has also done a complete 180, as his BABIP has swung to the fortunate side, currently sitting at just .190. His sinker velocity is up again, but his SwStk% hasn’t changed, so he still appears to be the same pitcher as always, just with a reversal of fortunes. I remain just as optimistic as I was in the preseason when I rostered him in two leagues that he’ll deliver positive fantasy value this league regardless of league format, but don’t get carried away.

What do you get when you combine a career high GB% with a career high SwStk%? A potential Anthony DeSclafani breakout. All those swinging strikes haven’t yet led to a jump in strikeout rate, but at least he’s seemingly put last year’s disastrous performance behind him. He has adjusted his pitch mix a bit, but not significantly enough to expect such a change in GB%. But like I’ve noted on Mize, most of this is due to a big drop in LD%, which is simply not sustainable, so many of those grounders will likely become future liners and flies. That said, he should earn positive fantasy value all year and be a solid streaming option at the very least in shallow mixed leagues, especially during his home games.

Add German Marquez to the list of superficial GB% risers. His FB% is almost exactly the same as last year, so once again, he’s traded liners for grounders. Obviously, this is a good thing for his actual performance, but it’s not sustainable, especially given a home park that inflates line drive rate. Marquez’s results have been strong so far, but his fastball velocity is down, his SwStk% has dipped into the high single digits after being perched above 12% for three straight seasons, and suddenly he has lost his control. I would be cautious about starting him in mixed leagues.

It’s amazing how long it took Nathan Eovaldi to turn his premium velocity into swings and misses and strikeouts. This year, he’s adding lots of grounders to his new whifftastic profile, and unlike some of the others above, this is a true increase. Suddenly, Eovaldi is sporting an elite skill set. But don’t forget, he’s only thrown more than 150 innings in a season twice, and the last time came all the way back in 2015.

C’mon Corbin Burnes, give opposing batters a chance! Yeesh, his skill set looks like that of a dominant reliever as it’s almost impossible to imagine a starting pitcher being this good. His GB% and FB% are up this year. Why? Because he’s only allowed a microscopic 6.7% LD%.