Lift-Off for Christian Yelich

Monday, I wrote about why, if I had a vote, I’d select Jacob deGrom for National League MVP. I do not have a vote, though, and I doubt that my argument is sufficiently convincing. The NL MVP is almost certainly going to end up being Christian Yelich. There was a somewhat crowded field for a little while, but Yelich pulled away from his fellow position players with an impossible final month. From the start of September, Yelich batted .370, with 16 strikeouts and 18 extra-base hits. Yelich was the best overall player from start to finish on a Brewers team that won the division literally yesterday. For what the MVP has turned into, Yelich is the obvious choice. Tremendous player on a team that wouldn’t have gotten to where it did without him.

Truth be told, it also wasn’t just the last month. Yelich was baseball’s best hitter in the second half, and it wasn’t even close. After the All-Star break, he registered a wRC+ of 220. Baseball Reference doesn’t keep track of wRC+, but it does keep track of OPS+ and its splits do go back further than ours, and according to the numbers at Baseball Reference, Yelich had one of the ten or so best second halves in the last 50 years. The only players with better second-half rate stats over enough of a sample: Barry Bonds, Mike Schmidt, Hank Aaron, and Jim Thome. Bonds actually has the four best second halves, and they all happened in a row between 2001-2004, but this isn’t a Barry Bonds fun-fact article. This is a Christian Yelich fun-fact article. He did his best to carry the Brewers into the NLDS.

Obviously, Yelich was already good. The Brewers traded for Yelich because he was already good. Good and somewhat underrated. But here’s a glimpse of Yelich’s big-league career, in terms of rolling wRC+. Yelich has been especially good before, but not like this.

Through the first week of May in 2016, Yelich had a 171 wRC+. Recently, he’s been a lot better than that, for a lot longer than that. It’s reasonable to wonder, therefore, if this is more than just a random and well-timed performance spike. Every single player’s performance will move around in both directions. But it generally won’t move *that* much without something being up. Given that this is Christian Yelich we’re talking about, you knew you weren’t going to get through this post without finding the words “launch angle.”

Historically, Yelich has made really good contact. Historically, Yelich has hit a ton of ground balls. Historically, people like me have wondered what might happen if Yelich hit more balls in the air. You already know all that. So let’s consider Yelich’s 2018, with the help of Baseball Savant. Here, you’ll see everyone’s first-half and second-half launch angles, and Yelich is in yellow.

That’s interesting, in that it’s not interesting. Before the break, Yelich had a launch angle of just about four degrees. After the break, Yelich has had a launch angle of just about six degrees. Higher, sure, but not by much. We don’t really care about such small launch-angle changes. Based on this little analysis, then, you might be inclined to look somewhere else. And yet — and yet, looking at something related but different, you can see how Yelich’s ground-ball rate has dropped off.

Yelich has been hitting fewer grounders than ever. He has a career grounder rate of 58%. He had a 2017 grounder rate of 55%. He just put up an August grounder rate of 46%, and a September grounder rate of 44%. You might ask, how is this possible, given the tiny change in overall launch angles? Wouldn’t launch angles provide a more accurate measurement? Not necessarily. Consider four batted balls. Their launch angles are -10, -10, +20, and +20. You’d have a grounder rate of 50%, and an average launch angle of +5. Now consider four different batted balls. Their launch angles are -30, +10, +20, and +20. You’d have a grounder rate of 25%, and an average launch angle of +5. The second group would be far more productive than the first.

I’ll try to simplify this a little bit. Yelich’s launch angle hasn’t changed all that much, on average. But there has been a change in his so-called quality contact. This time, instead of looking at all launch angles, let’s look at everyone’s average launch angles just on batted balls hit at least 100 miles per hour. This might give us a better understanding of intent; it’s tough to hit a ball that hard by accident. Once again, Yelich is in yellow.

Now we’re seeing something. In the first launch-angle plot, there were 311 players in the sample, and Yelich ranked 73rd in first-half to second-half improvement. In this second launch-angle plot, there are 137 players in the sample, and Yelich ranks second in first-half to second-half improvement. When Yelich hit a ball at least 100 miles per hour in the first half, those batted balls had an average launch angle of +5.5 degrees. When Yelich hit a ball at least 100 miles per hour in the second half, those batted balls had an average launch angle of +15.0 degrees. The only player with a bigger positive change down the stretch was Jorge Alfaro. Yelich certainly wasn’t trying to hit everything a mile high, but it does seem as if he was intending to direct his better contact into the air. As discussed in the introduction, it worked. Yelich became a wrecking ball, systematically destroying his opponents.

One last plot: how Yelich has fared in this regard over the last four years of his career, as captured by Statcast. This is a launch-angle rolling-average plot, considering only those balls he hit in the triple digits.

We have a new high peak. There are two other obvious, earlier peaks. As always, numbers bounce around, and perhaps Yelich has tried to hit for this kind of power before. Recently he’s gotten up to a new level. He’s still getting the barrel to the ball as always, but those balls are exiting a few more degrees above the horizontal. Yelich has been eliminating a chunk of his grounders. He doesn’t want to be hitting so many grounders. He’s still more of a line-drive hitter than a true fly-ball hitter, but a line drive can be good for a double, and a slightly higher line drive can be good for a homer. Especially when you hit the ball as hard as Yelich does. He didn’t have to make so dramatic a change to improve as a power threat. It’s more about intent and selectivity. Everything has led up to this point, where the Brewers are going to the NLDS, and Yelich is reaching his offensive ceiling.

I’m sure at some point it got kind of annoying to keep reading about Christian Yelich and his ground balls. Yelich didn’t have to change who he was, because he was already very good. And it’s not like now Yelich is a true-talent 220 wRC+ kind of hitter. Barry Bonds was a true-talent 220 wRC+ kind of hitter. Christian Yelich isn’t Barry Bonds. He’s going to fluctuate. But this is precisely what made Yelich so intriguing in the first place. This is why Yelich has been a popular subject since the early days of Statcast. Yelich always made you wonder: what if? The Brewers and the rest of us are all finding out.