Is speed really that important, Part II

Two weeks ago, I said that speed wasn’t all that important.  Oh sure, it plays some part in a runner succeeding when he tries to take an extra base, but it’s a rather small part.  I looked at a few situations in which speed might come in handy (e.g., going from first to third on a single, stealing a base) and found that speed (as measured by Bill James’s speed score method) only predicted a small amount of variance in success rates.
Does speed predict whether or not the manager/third base coach will send the runner in the first place, though?  Yes, it does, and actually speed is a better predictor of whether or not a runner will be sent than whether or not he will make it.  I looked at four situations in which a manager/3B coach actually has to make the decision to send the runner (1st to 3rd on a single, 2nd to home on a single, 1st to home on a double, and stolen base attempt), and looked to see whether an attempt was made in each situation where the relevant circumstances were present.
First to third on a single: attempt R-squared, 1.4%; success R-squared, 0.2%
First to home on a double: attempt, 2.0%; success, 1.0%
Second to home on a single: attempt, 1.7%; success, 1.2%
Stolen base (of 2nd): attempt, 10.2%; success, 4.2%
Speed is a much better (although that’s a very relative term) predictor of whether a runner will be sent than whether he will make it.  Still, speed isn’t predicting a whole lot of the variance.  For those of you not familiar with this methodology, this doesn’t mean that MLB teams are sending everyone.  (Far from it… from 2000-2006, the “send” rates were 31.8%,  45.3%, 63.0%, and 7.1% respectively).  It just means that when deciding whether or not to send the runner, speed is something like 2% of the decision with the ball in play and 10% of the decision for a stolen base attempt.
With a stolen base attempt, there are some situations in which a manager wouldn’t attempt a stolen base, even with Jose Reyes at first and Mike Piazza behind the plate.  If someone’s up 16-1, there’s an unwritten rule that you don’t try to steal there.  I restricted the sample to the first three innings when it’s generally more respectable to try to steal, although this only bumped up the R-square to 11.4%.
So, if not speed, what are coaches looking at in making their decisions?  My guess is that when the ball is live on the field, they’re again looking at where the ball is.  When I did a study on sac flies, where the ball was in the field explained about half(!) of the variance in whether or not the runner was sent.  So, if you cheer for a team where they keep a guy around just because he’s fast, write to the general manager and question his sanity.  Not only is speed a huge factor in whether or not the runner will make it, managers aren’t even really looking much at speed anyway.


Leave a Reply

Fill in your details below or click an icon to log in: Logo

You are commenting using your account. Log Out /  Change )

Google+ photo

You are commenting using your Google+ account. Log Out /  Change )

Twitter picture

You are commenting using your Twitter account. Log Out /  Change )

Facebook photo

You are commenting using your Facebook account. Log Out /  Change )


Connecting to %s

%d bloggers like this: