Footspeed and Forcing Errors: A Case Study

Defensive errors have been a part of baseball history forever, but we seldom ever talk about them now. We’ve come to better understand the importance of range, and so we look beyond errors for our defensive evaluations. A guy might make an extra error or two simply because he’s covering a lot more ground than a peer. There’s also the matter of errors being subjective, some being obvious calls and some being coin flips. As for hitters, errors are mistakes by the other team. When a hitter smacks a ball in play and the defense makes an error, we tend to think of the hitter as lucky, because that shouldn’t have happened. So hitters don’t get a lot of credit.

But errors do happen, and they’re factored into some wOBA formulas, and there’s a line of thinking that faster runners can force more defensive errors, giving them a mostly unseen advantage. There’s the idea, then, that there’s indirectly some skill involved, which might mean a few extra runs. I, personally, have seen Ichiro reach a bunch of times on misplays, which might’ve had to do with his speed. The more a defender has to hurry, the more prone he might be to screwing up, which could be a thing worth talking about. We’re about to focus on Norichika Aoki.

Baseball-Reference has a Play Index, which can be really nifty. Within the Play Index, there’s an Event Finder, and within the Event Finder you can search for instances of hitters reaching on errors. A search this year turns up 789 instances, with Jordan Zimmermann having the most mistakes behind him among pitchers. For hitters, Norichika Aoki has reached on errors a dozen times. No one else has reached more than eight times, making for a pretty significant difference. Last year, Aoki was tied for third in baseball in reached-on-errors, and now it would be reasonable to conclude there might be something about Aoki that’s causing this.

Aoki’s a pretty good baserunner, and he bats left-handed, meaning he gets down the line quicker than a righty. He also hits a bunch of balls in play on the ground, giving the defense more opportunities. I decided to look at all 12 of his 2013 reached-on-errors, to see if they might’ve been caused by his running. This is going to be a subjective exercise, but it’s an exercise with a lot of .gifs so at least it’ll be visually appealing after it finally loads. I guess we’ll get started and go in order.

Error 1: April 9

Well this wasn’t about Aoki at all. The defender was committed to throwing home, and it was really really cold out. So that’s going to happen sometimes.

Error 2: April 9

This was an ugly bobble on a routine grounder, although the hurried throw might’ve had something to do with Aoki sprinting down the line. It was in the same game as error no. 1, so it was freezing, so throwing was a challenge. But Aoki might’ve made a contribution here, after the defender’s initial mistake.

Error 3: April 19

Can’t really put that on Aoki’s speed. That’s just defending like an idiot. Maybe it was in the back of the first baseman’s mind that Aoki would get there in a hurry, but you realize now how hard it is to figure out where speed did and didn’t make any difference.

Error 4: April 20

Plenty of time; just an ordinary fumble. The shortstop doesn’t look to be rushing.

Error 5: May 2

Basically unrelated to Aoki. This is a disaster of an attempted double play.

Error 6: May 4

This isn’t even an error. This is just a fielder’s choice that didn’t work out for the fielder. I don’t know why this is here in the Event Finder results but, all right, nothing to do with Aoki, at least.

Error 7: May 11

Ordinary mistake trying to backhand the baseball. Could’ve happened with anyone at the plate.

Error 8: May 13

This wound up being a hurried throw, because Aoki was almost to the bag, but this was screwed up well in advance of that part. It’s basically a shame there was only one error on this play. There was one bigger umbrella error, with several individual component errors.

Error 9: May 20

This all looks routine, and the shortstop isn’t rushing anything. It’s just a bad throw that he makes, and the throw isn’t snared at first. Aoki would’ve been out were the throw on the target.

Error 10: May 22

Maybe, the shortstop was hurrying because the grounder was soft and it was Aoki going down the line. Or maybe this is just a regular fumble. I think this play is always at least a little hurried.

Error 11: May 26

Unrelated to Aoki. Just a blown double-play attempt.

Error 12: June 2

Yeah, that’s not Aoki. That’s a second baseman getting ahead of himself when thinking about a double play. That easily could’ve and should’ve been a 4-3 DP, and the defender had plenty of time, but his brain just checked out.

Obviously with something like this, it’s impossible to isolate the influence of the speed component. We can’t get in the defenders’ heads, and if a defender is hurrying, we can’t know if he’s doing so with a specific runner in mind, or if he’s just hurrying for hurrying’s sake. You could say, then, this exercise was never going to go anywhere. We just can’t accurately interpret the plays. But note that only a few of the errors above had to do with Aoki himself. His speed probably made a difference with a few of these, but not with most.

What’s probably a more important factor? Aoki puts everything on the ground and he never strikes out. He has, at this writing, baseball’s lowest strikeout rate. He leads all of baseball in total groundballs by a good margin, and errors are mostly a product of opportunities. More interesting would be errors per ball in play, or errors per grounder if you assume that fly-ball errors are flukes. And then you’d have to control for baserunner state, since there can be errors on attempted force outs.

How can you predict how often a guy will reach base on error? Look first at his rate of grounders per plate appearance. Then, it probably matters if he’s left-handed, then, it probably matters if he runs well. It would be silly to assume speed doesn’t make any difference, but it’s only fractional. Albert Pujols has reached on error seven times this year and he’s been running like he’s hauling a wheelbarrow of bricks. Errors are almost random and they happen for a variety of reasons, and speed is just one of a bunch.

For as long as he’s playing, Norichika Aoki is probably going to reach base on errors pretty often. Odds are, that’s going to have at least as much to do with his bat as with his legs.