February 22, 2013 at 10:00 am by Mark Smith under Atlanta Braves
One of the most commonly misunderstood things about baseball analysis is what is meant by luck or random variation. Neither of those terms truly describes what’s happening. Sometimes, players really do suffer from rotten luck – broken bat singles, line drives right to the shortstop, great diving/home-run robbing catches – and if you think the world generally evens things out, you need to look at the world again. Sometimes, random variation happens – hit a ball hard in Arizona and it goes out while you hit it as hard in Petco and it doesn’t – and you can’t always control when certain things happen. What most people mean by luck and random variation is that, given enough time, so many events will happen that things will get relatively close to evening out. But a lot of times there are reasons why players go into slumps, and yet, we still expect things to even out. Let’s look at Jonny Venters to explain.
Venters 2012 first half didn’t go according to plan. By the All-Star Break, the sinkerballing reliever who had ERA below 2.00 in his first two seasons saw his ERA skyrocket over 4.00 to almost 4.50. Looking at his peripherals, however, told us not to worry. His strikeout rate was near 12 per 9, and his walk rate was near 4.5. Considering his career marks are 10 and 4.5, Venters’ stuff seemed to remain strong despite losing a mph off his pitches. Batted balls? Well, his GB/FB rate was 3.79, which was down from his career rate near 4.50, but that seems like a slight change for such a dramatic difference in ERA. But Venters also gave up a lot of home runs. Was something off causing that?
First thing is to look at pitch location.
While Venters wasn’t as good in 2012 as 2011, he wasn’t really much worse than he was in 2010. What about differences in pitches?
Again, the sinker isn’t as good as 2011, but it’s still not that drastic of a change. The slider?
Welp. Not much difference there, either. But these are for the entire season, and in many ways this backs up the “he’ll be fine” idea. Over the course of the season and because the overall peripherals were okay, chances are that he was going to recover, which he did. But what about the first half vs. the second half?
Now we see some difference, and we should note a couple things. The first thing is the drastic shift in location between the two. In the first half, Venters was often throwing to the glove side of the plate, and when he threw it to the arm side, he might as well have started screaming, “Back, back, back” as soon as he threw it. Going to the second half, his pitches return the lower area of the arm side of the plate, and the location is very concentrated. The second thing we should note is that Venters’ first half is a severe departure from his career strategy, while his second half was much more similar to his career. Why did this happen?
The immediate suspect was his “elbow impingement”. This injury doesn’t allow the elbow to extend in a normal way, which certainly seems like it could have been a problem. Was it?
Well, it didn’t affect his release point. What about movement?
Ah, here we go. Notice anything? Look at the sinkers (the pinkish triangles). You should notice a few things. One, they’re more concentrated, which means he was getting consistent movement. That’s helpful with things like hitting your spots. Two, the movement is more vertical instead of horizontal. For some reason (be it injury or mechanics), Venters’ sinker was flattening out in the first half. Instead of diving, it was sliding, and when it slid, it stayed belt high instead of going to the knees. If you have trouble locating and often locate farther up when you’re trying to sink the ball, you’re going to (or at least you should) give up harder contact, fewer groundballs, and more home runs. Did he deserve a 43% HR/FB rate? Probably not, but this certainly explains why he gave up more home runs and, thus, more runs.
But here’s the thing – Venters and the coaches down in that clubhouse are not idiots. Whether they pore over PITCH f/x charts or not, they probably noticed that Venters wasn’t hitting his spots and that his sinker wasn’t sinking as much. As a result, they probably looked at more film to see what was wrong, and when they did, they tried to fix it. Perhaps the mechanical changes weren’t having an effect because the impingement wasn’t allowing him to throw his pitches the way he wanted. It really doesn’t matter. The point is that baseball, like many sports, is a game of adjustments. Sometimes it’s adjusting strategy. Sometimes it’s making physical adjustments to deal with injury. But it happens to every player in every season. When things are going great, you let it ride, and when they go poorly, you work to correct it. But by the end of the season, we expect that the results will be similar to the year before because guys have hot streaks they can’t sustain and slumps they won’t endure. Sometimes it’s luck. Sometimes it’s random variation. And a lot of times there are actual things going wrong that probably won’t stay wrong long.