Corey Dickerson Has Broken the Rules

It can be a bit tricky to do this job from the west coast. As soon as you wake up, you’re behind, and I find I always have to begin my days reading. On the plus side, it’s usually reading I’d have to do anyway. Also on the plus side, you never know where you might find an idea. Earlier today, I was reading Eno’s latest post, on Joey Votto and Jay Bruce. Not only did the post provide excellent insight — it also took me back to something from last July. Eno was talking to Bruce about shifts, and using the whole field. An excerpt of a response:

But you hear people talk all the time, ‘I don’t know why he doesn’t just hit the ball to left field, or bunt.’ Well, the shifts are getting more sophisticated, where the third baseman is playing in. And the other guys are over. How many guys do you really know that hit for power that hit ground-balls to the opposite side of the field?

This is data I’ve played with a little before. Nori Aoki, for example, hits a ton of grounders toward the opposite field. Aoki also has 19 career home runs. Not a power threat. You already know many of the guys with stronger pull tendencies on the ground. They see a lot of shifts, and the group includes players like Chris Davis, Ryan Howard, and David Ortiz. But let’s see about answering Bruce’s question. Are there any powerful hitters who send grounders the other way? I know I already ruined the surprise before I even started the body of the post, but, do play along, won’t you?

You could’ve guessed this, but, absolutely, there’s a link between hitting for power and pulling or not pulling grounders. I looked at numbers from the past three seasons, and I selected hitters who’ve put in play at least 100 grounders over that span. I then calculated their opposite-field-grounder rates (OppGB%), which is possible to do using information from the FanGraphs leaderboards. I sorted the players — all 465 of them — by z-scores. For the record, the average OppGB% is a hair below 13%. Here’s a table showing the link in one direction between OppGB% and ISO, where each of the five groups includes 93 players:

Group	OppGB%	ISO
Group 1	19%	0.101
Group 2	15%	0.125
Group 3	12%	0.146
Group 4	10%	0.159
Group 5	7%	0.172

As OppGB% goes down, power output goes up. There’s nothing groundbreaking here. For some reason, here’s a table showing the same link in the other direction:

Group	ISO	OppGB%
Group 1	0.208	10%
Group 2	0.165	10%
Group 3	0.141	12%
Group 4	0.112	14%
Group 5	0.076	16%

In the first table, the players were grouped in order of OppGB%. In the second table, the players were grouped in order of ISO. Shown here: as power goes down, OppGB% goes up. Same deal. So we’ve established the relationship. As you can imagine, this has a lot to do with swing paths. It’s not easy to hit a grounder the other way, and it’s especially not easy if you have a swing designed to launch the baseball 400 feet. Now, is there anything to be said about exceptions?

This graph is showing you the same information. All this does is display the inverse relationship between power and opposite-field grounders. But you see that one point is highlighted. The whole player pool doesn’t fall right on the best-fit line, and no one is further from the best-fit line than Corey Dickerson. Dickerson has hit 20% of his grounders toward the opposite field, nearly two standard deviations from the mean. He’s also posted a .237 ISO, precisely two standard deviations from the mean. Granted, ISO isn’t park-adjusted, and Dickerson has played half the time in Colorado, but if you apply a quick adjustment, his ISO stays over .200. The best-fit line would predict an ISO of .096.

Taking all the players with an ISO at least one standard deviation above the mean, here are the highest opposite-field-grounder rates:

• Corey Dickerson, 20%
• Ryan Zimmerman, 19%
• Ian Desmond, 17%
• Matt Holliday, 16%
• J.P. Arencibia, 16%
• Ryan Braun, 15%
• Bryce Harper, 15%
• Robinson Cano, 15%
• Justin Upton, 14%
• Tyler Colvin, 14%

Dickerson isn’t the only exception. And you’ll notice a few Nationals on there, so maybe that’s a thing worth examining. But Dickerson stands as the most extreme exception, over the three-year window investigated. It’s not the easiest thing in the world to explain why, but at least visually, you can see he has an unusual swing:

Dickerson knows he has an uncommon swing path. I’ll leave it to Dan Farnsworth or someone to go into detail. I’m not going to break down Dickerson’s swing because I’m not qualified to do that, and I’m sure I’d get a lot of things wrong. What we have is the result. Dickerson has hit pitches a little differently. So his hit distribution has been a little different. Some of it just comes from the ballpark, but that doesn’t explain everything entirely. He’s hit the ball to all fields, he’s hit the ball on the ground to all fields, and he’s also hit for power. Dickerson has never been considered much of a prospect, despite his results, and maybe scouts were just thrown by an unfamiliar-looking swing. Through 700 big-league trips to the plate, Dickerson’s posted a 127 wRC+.

Something we can’t speak to is sustainability. Because I’ve never done much with this data, I don’t know how meaningful it is when it comes to seeing into the future. On the one hand, this could mean Dickerson is going to continue to exceed expectations. He might continue to be an exception to an otherwise pretty stringent rule. Or maybe this just means Dickerson is a good bet to have his numbers regress. Could be, he hits for less power. Or, could be, he hits fewer opposite-field grounders. What he’s done isn’t done often, and that’s enough to make one wary. But if nothing else, we’ve uncovered an answer to Jay Bruce’s question from last July. Corey Dickerson. Corey Dickerson is one.