Pitcher Ground Ball% Changes — May 7, 2024

Like discussed with hitters yesterday and last week, a pitcher’s batted ball type profile is important and helps drive their BABIP and HR/9 rate. More grounders and line drives allowed usually result in a higher BABIP, while more fly balls allowed usually result in a higher HR/9 rate. So with that in mind, it follows that changes to a pitcher’s profile could change the shape of their performance. Let’s review the five starting pitchers that have raised their GB% the most, along with those who have suffered the biggest declines.

Michael Lorenzen has been the season’s biggest GB% gainer so far, though this isn’t really out of character for him. He has posted a GB% over 50% four times before and his gains are inflated because last year’s 41% GB% was a career worst for him. Even with the increased GB%, his strikeout and walk rates stink and he has overperformed both his SIERA and xERA. I wouldn’t even want to start him in an AL-Only league as he’s not even providing strikeouts if his ratios implode as his expected ERA metrics suggest is possible.

I remain angry at myself for somehow forgetting to save a spot for Chris Sale on my teams. His skills are as strong as they’ve been, while his GB% is sitting at its highest mark since he was a full-time reliever all the way back in 2011. With his fastball velocity also jumping, he’s looking like a major profit. Obviously, there’s no telling when or if he’ll hit the IL, but enjoy the performance while he’s healthy.

This is currently a career best GB% for Trevor Williams, who has also managed to reduced his LD% to a career low. The batted ball profile change looks like a positive, but it’s still not enough to explain his smoke and mirrors act so far. He has posted a 2.27 ERA, despite weak strikeout and walk rates, while his SIERA stands at an inflated 4.61 and xERA at 3.28, a mark far better than I expected to see. Most of the good fortune is the zero home runs allowed, which obviously won’t last. I wouldn’t touch him, regardless of league format.

Reese Olson is one of those “fake” gainers. You like to see a decline in FB% to pair with the increased GB%, but here, it’s almost all from a reduced LD%. Of course, that’s a good thing so far, but it’s just not sustainable. So we have to assume the LD% will go up, reducing his GB%, and possibly his FB%. But since his FB% is mostly in line with his history, I’d bet his GB% will take the biggest hit. Williams above has done something similar, but not as dramatic a degree. Based on the results, it looks like Olson is in the middle of a breakout year. But, his strikeout rate is a bit lower, while walk rate is up, so the skills haven’t actually improved. Once again, it’s all down to the zero homers allowed. I think the skill set here is solid, but it’s nearly identical to last year, so I wouldn’t change my preseason opinion here at the moment.

Ranger Suárez has done this before as well, but is coming off a down GB% last year. The more exciting thing is a career best strikeout rate, combined with a microscopic 3.5% walk rate. I doubt that lasts, but he’s pushed his SwStk% back into double digits to justify the increased strikeout rate. That’s surprising though, as his velocity is actually down and his pitch mix hasn’t budged. I don’t expect this skill set to be maintained.

Grayson Rodriguez has essentially reversed his GB% and FB% marks compared to last year. It’s a good thing the renovated Oriole Park is now much more pitcher friendly, because such a FB% back then would have been a killer. All those extra flies have also resulted in an IFFB% spike, which means lots of pop-ups, and a real benefit to BABIP…you would think. Instead, his BABIP has jumped even higher than last year’s inflated mark to .344. That’s not what more flies and pop-ups are supposed to do! Amazingly, his strikeout rate, SwStk%, and CStr% are all almost identical to last year. Heck, even his walk rate is identical! I like this profile for him better, as it works in one of the league’s toughest parks to homer in.

Before hitting the IL, Steven Matz had traded grounders for line drives. That’s not good. So he’s another “fake” GB% decliner, as his FB% is right in line with past seasons. Matz’s strikeout rate has plummeted this year, despite normal velocity and only minor pitch mix changes. I don’t know what’s going on here, but he’ll be a risk to start, if anyone even was, when he returns.

George Kirby had posted pretty league average batted ball type rates, but he’s become a fly ball pitcher this year. Like Rodriguez, that’s not a bad thing in a home park that marginally suppresses home runs. The FB% might even increase as his LD% is up and some of those liners could become flies moving forward. It’s amazing to me that he could manage a 26.3% strikeout rate, despite a pedestrian 26.8% CSW%, but he’s never been much of a CSW% guy. For as long as he displays elite control and tiny walk rates, he’ll be good, but I’ll typically prefer a more traditionally dominant pitcher at the same cost.

This is the lowest GB% Sean Manaea has posted, as both his LD% and FB% now sit at career highs. He has also oddly struggled to induce pop-ups, as his IFFB% is at a career low, which you don’t normally see paired with a career high FB%. Possibly the scariest thing in his profile is that 14.1% walk rate. That’s more than double his career mark and could be a major red flag if it doesn’t improve in quick order.

Tyler Glasnow rounds out the “fake” changes, as we’re comparing to a career high GB% last year. His profile is only slightly different than his career marks, with a slightly lower GB%, and slightly higher LD% and FB% marks. He’s been elite on his new team, doing what he always does, and has managed to stay healthy for the time being. In shallow leagues, he should always be a prime target as it’s easier (though not easy!) to replace his production than in deeper leagues.