Do fast runners protect hitters behind them?

One of the interesting insights that Joey Votto offered in Eno Sarris's interview at the end of March was the idea that having Billy Hamilton offered lineup protection.  This was a neat insight, and it makes sense: with Hamilton on first base, pitchers are more likely to throw fastballs to the batter to give their catchers a chance to throw them out, and certainly will avoid burying sliders and curveballs in the dirt.  That gives the batter a better shot at getting a good pitch to hit.

It does fly in the face of some past research, however.  In The Book, Tom Tango et al found that hitters actually hit WORSE with speedsters on first base than without.  Presumably, this effect was because they were distracted by the baserunner's antics as much as the pitcher would be.  There's on-the-field precedent for this as well: Joe Morgan famously demanded that runners hitting in front of him not steal bases while he was batting because of this distraction.  

So which is it?  Ben Lindbergh took another look at this yesterday...and found support for both arguments.  Sort of:

• Batters do see more fastballs with speedsters on first than with basecloggers on first (71% vs. 67%).  

• But despite seeing more fastballs, batters hit WORSE with speeders on first than with basecloggers (.273 TAv vs. .281 TAv)

Ben also pointed out that in The Book, they found that older batters were less distracted than younger batters.  So, hitting despite distractions might be something that can vary across hitters, and is something that hitters can learn to do.  Votto might be particularly good at it.  And really, if there's someone who would be good at this, it'd be Votto.

I might also expect, based on where their eyes are looking and their angle from the plate, that this distraction would be largest for righthanded hitters batting against left-handed pitchers.  Maybe if I get a play by play database running this summer with my Sabermetrics class, this might be something to look at!