What Christian Yelich Has Changed by Jeff Sullivan August 30, 2018 You couldn’t blame Eric Hosmer or Christian Yelich if they got sick of hearing about Statcast. Anyone who’s ever played with the basic tools has been able to discover two things: (1) historically, Hosmer and Yelich have hit the ball hard, and (2) historically, Hosmer and Yelich have hit the ball on the ground. It became easy to wonder what might happen if Hosmer and Yelich set their sights on the skies. It just so happened that, last offseason, both of those players changed teams. Might they have also been willing to change their swings? It’s not that it wasn’t interesting. It just started to grow a little tired. Hosmer hasn’t changed. That much I can tell you. Through five months of baseball, he’s got a below-average batting line and a below-replacement WAR. He has the highest ground-ball rate he’s ever posted. But then, Yelich is currently sitting on a career-high wRC+. He’s sitting on a career-high slugging percentage. He’s also technically sitting on a career-low ground-ball rate. Don’t get the wrong idea, though. Yelich’s average launch angle hasn’t budged from last season to this one. He remains a ground-ball and line-drive hitter. In part, he’s just benefiting from playing in Milwaukee instead of playing in Miami. And in part, he’s benefiting from another change. It’s not one that has to do with his swing. Rather, it’s one that has to do with his approach. Yelich has been particularly good over the past two months. It all led up to Wednesday, when he finished 6-for-6 while hitting for the cycle. Granted, through June, Yelich had a terrific 123 wRC+. But since the start of July, he’s up at 184. Out of everyone with at least 150 plate appearances over the same time span, Yelich has ranked as the third-best hitter, and he’s been doing his best to keep the Brewers’ offense afloat. Barring a disastrous final stretch, Yelich is going to drum up some measure of support for the NL MVP. I’m not here to argue whether Yelich is or isn’t the most valuable player. The most important games are still ahead of us. Instead, I want to show you what Yelich has been up to. Yelich batted six times against the Reds on Wednesday. The first three times up, he swung at the first pitch. The last three times up, he took the first pitch for a ball. The third time he swung at the first pitch, incidentally: And here we can see how Christian Yelich has changed. He’s been in the majors for a while, having batted more than 3,300 times. With the help of Baseball Savant, here’s a plot of Yelich’s career first-pitch-swing rates, expressed as 100-plate-appearance rolling averages: The recent Christian Yelich has reached a new height, and you can see how this is a newer development. In the past, Yelich went after the first pitch roughly a fifth of the time. That was more patient than the overall average. Here are his 2018 monthly splits: April: 20% first-pitch-swing rate May: 22% June: 24% July: 30% August: 41% Yelich turned it up in July, and it’s only grown more extreme in August. Now, maybe for something like this, you’d appreciate the additional benefit of context. So here’s the same idea, except this time I’ll show you Yelich’s percentile ranks among his peers: April: 22nd percentile first-pitch-swing rate May: 24th June: 31st July: 55th August: 91st Yelich has gone from being particularly patient to particularly aggressive. He’s done this essentially on the fly. Through June, Yelich had 10 hits on the first pitch, which tied him for 99th place in the majors. Since the start of July, Yelich has 18 hits on the first pitch, tying him for first place in the majors. Looking at it again, through June, Yelich had six extra-base hits on the first pitch. Since the start of July, he has a league-leading 10. For the sake of reference, all of last season, Yelich had five extra-base hits on the first pitch. The year before that, eight. The year before that, seven. The year before that, five. Yelich has done in two months what he hadn’t previously done over six. And while this might be a minor thing, Yelich seems to be swinging early with intent. I mentioned that Yelich’s overall launch angle hasn’t really changed. That much is true. But look at four years of his launch angles on first-pitch batted balls: 2015: +1.7 degrees 2016: +3.2 2017: +4.5 2018: +11.2 Yelich has always kind of had two swings — there’s the swing that sprays a ball the other way, and there’s the pull-power swing, the one that can hit a ball 440 feet. Yelich has been hitting the first pitch better, and he’s been going after the first pitch more. He’s been taking the more aggressive hack while he has some pitches to play with. Many hitters wouldn’t want to take the same chance when they already have one or two strikes. Truth be told, this is sort of a proxy. What I’ve been focusing on are first-pitch swings. But lately, Yelich has been more aggressive in general, in zero- and one-strike counts. And while I can’t crawl into Christian Yelich’s head, what this suggests to me is that he’s simply made an effort of late to go into the box ready to swing. He’s more ready to punish the first pitch, which then leaves him more ready to punish the second or third. In that way, it’s psychological, but it also might be increasingly wise in this era of putaway pitches. This is the age of strikeouts, where everyone throws 95 with a breaking ball. The Red Sox have worked to be aggressive early in the count. The Braves have worked to be aggressive early in the count. Yelich is there, as well, trying to get to the pitcher before the pitcher can get to him. These things are always cyclical, but this has been driving Yelich’s success. As Yelich has been more aggressive, he’s been more able to pull the ball toward right and right-center. And as he’s been more able to pull the ball toward right and right-center, his power numbers have skyrocketed. This version of Christian Yelich still hits plenty of balls on the ground. This version of Christian Yelich might take a hack or two too many out of the zone. But this speaks to how good Yelich really is: A switch flipped for him a couple months ago, and he’s tweaked his approach on the fly. Yelich goes up there ready to swing these days, which means the opponent can’t take a single pitch off.