When deciding whether or not to draft a speedy hitter to our daily fantasy baseball team on any given day, we tend to focus a lot on the catcher he’ll be facing.  Avoid anyone facing Yadier Molina and the Cardinals or Joe Mauer and the Twins.  Don’t worry as much if Ryan Doumit is behind the plate for Minnesota, though.  This is generally good practice, but the catcher isn’t the only one involved in stopping the running game. The pitcher's handedness can also be a factor.

The pitcher is also involved and can play a very important part, either for better or for worse.  Chris Young is one of the most extreme examples in recent history, catching just 9 percent of would-be base stealers (league average is 27 percent).  Pitchers control the running game with things like a slow/quick delivery or a good/bad pick-off move, but even if you don’t know anything about this sort of thing, there’s one very basic bit of information that can help you decide whether it’s worth playing a speedster on any particular day: the starting pitcher’s handedness.

The pitcher’s handedness determines whether he faces first base or third base while he’s on the rubber (righties face third while lefties face first).  Naturally, it’s a lot easier for the pitcher to see what the runner is doing if he's facing him and not having to worry about looking over his shoulder. As a result, it is a lot easier for lefties to control the running game.  But how much better are they at it than their right-handed counterparts?  Let’s check out some numbers, collected using all MLB pitchers over a recent seven-year period.

Stolen Base Data by Pitcher Handedness

Note: SB stands for Stolen Base; SBA stands for Stolen Base Attempt; SBO stands for Stolen Base Opportunity.  These numbers are only derived using attempts, opportunities, and steals of second base.

As you can see, the numbers do indeed bear out our hypothesis that left-handed pitchers are better at preventing stolen bases than right-handed pitchers are.  The difference isn’t quite as stark as I expected, but consider that these numbers are derived from an aggregate "league average" runner.  In a minute, we’ll run some back-of-the-envelope math for an elite base stealer (the guys these kinds of decisions are most applicable to, since their inclusion on your team will be based largely on whether they’re a good bet to steal a bag), but first let’s look at these numbers in a more usable format:

Stolen Base Data by Pitcher Handedness, Relative to League Average

This table compares the rates for lefties and righties to the overall league average (including pitchers of both hands, formatted as actual percentage, not percentage points).  You’ll notice that the numbers for southpaws are further from league average than their counterparts -- this is because there are more righties than lefties, so righties are closer to league average since they make up something like 70 percent of it.  Because of this, what we’re looking at here is more a call to inaction than it is advice that you can use proactively.  Yes, there is some benefit to playing a speedster versus a right-hander, but it’s more important to avoid the speedsters that are facing lefties.

Now let’s look at an actual example with some back-of-the-envelope math.  Jean Segura is second in baseball with 37 steals this year.  He has a 25 percent SB/SBO rate.  Against a righty (+9 percent), we might expect that to rise to 27.25 percent.  That’s not bad, but it’s not really going to have much practical impact on your decision-making.  Against a lefty (minus-25 percent), however, Segura would be expected to drop to 18.75 percent.  That’s definitely worth taking into consideration and would probably keep you from drafting Segura to your team.

This is, of course, just one piece of the puzzle that is analyzing players for daily contests, but it’s one that needs to be considered.  When you combine all of these little pieces, that’s where you’re going to find big value.