Wednesday, April 1, 2009

Bad ball swingers

As the new season is ready to roll, I take some time to give away the 2008 Vladimir Guerrero Award.
Using Pitchf/x data I looked at the players who swing frequently at bad pitches, and I tried to figure if they hurt themselves by trying to hit everything.

Initially I planned to look at all swings occurred on a pitch that was a ball according to the rulebook strike zone; then I decided to do things differently.
Using spatial smoothing I calculated the probability of a pitch to be called strike, given it's location. A previous study I run on my Italian website, and other researches by other authors at THT and elsewhere, had showed that batter handedness influences umpire decisions more than pitcher handedness, so I calculated different probabilities for RHB and LHB.

A couple of charts will summarize this part.

I decided to classify a pitch as a "bad ball" when its probability to be called strike is lower than 10% (the cutoff value is purely subjective, and I'd welcome suggestions for a different choice).

Here are the top ten bad ball swingers:

LAST FIRST swing_pct
Soriano Alfonso 43%
Barmes Clint 42%
Headley Chase 41%
Span Denard 41%
Ramirez Alexei 41%
Aviles Mike 40%
Stewart Ian 40%
Gomez Carlos 39%
Uribe Juan 38%
Lowrie Jed 38%

No Vlad on the list? I must have done something wrong!... No, he's the eleventh, just out of the table, at 37%.
I compared my full list with the one at FanGraphs and while they don't coincide, they are quite similar. Anyway they don't have to coincide, since FG charts outside zone swing %, while I'm charting "really outside zone swing %".

Here's the bottom of the list.

LAST FIRST swing_pct
Matthews Gary 19%
Dellucci David 19%
Lewis Fred 19%
Murphy David 18%
Crede Joe 18%
Matsui Hideki 16%
Sexson Richie 16%
Upton Justin 16%
Castillo Luis 10%
Helton Todd 5%

For this work I selected players who have seen at least 300 bad pitches. I don't know if this choice caused some players who don't swing at bad pitches to be left out.

Next thing I investigated is run value for swings on bad balls.
Many players are notorious bad ball swingers, but they are also feared because they can do a lot of damage even when they chase pitches in the dirt.
In the following table I summed up the run values obtained by hitters when they swung at a bad pitch.

LAST FIRST swing_run_value
Sheffield Gary 9.37
Garko Ryan 7.28
Stewart Ian 5.86
Mauer Joe 4.99
Glaus Troy 4.87
Ortiz David 4.24
Cust Jack 4.02
Kubel Jason 3.95
Huff Aubrey 3.74
Hinske Eric 2.55

But what if all those pitches were let go by?
I calculated the net run value for bad pitches, which you will find in the next table, as following:
- if the batter didn't swing, assign the run value of the pitch (likely the run value of a ball; but if the ump called it a strike, then the run value of a strike);
- if the batter swung, assign the run value of the event minus the expected run value of the pitch had the batter not swung (that is something like 90+% * run value of a ball + 10-% * run value of a strike).

LAST FIRST net_run_value
Sheffield Gary 1.85
Stewart Ian -1.77
Glaus Troy -2.34
Hinske Eric -2.76
Cust Jack -3.08
Murphy David -3.39
Mauer Joe -3.84
Kubel Jason -3.85
Helton Todd -3.97
Bourn Michael -4.31

As we see from the table, Gary Sheffield is the only player in MLB to have a positive value for his bad pitch swinging (at 29% his swinging percentage on bad pitches is middle-of-the-pack). Jose Reyes, the worst in this ranking, has lost 32 runs by swinging at balls way out of the zone.
Players like Ryan Howard and Vladimir Guerrero can have a gross production of more than 11 runs when swinging at bad balls, but when you look at what they would have produced had they let those pitches go by you get a net loss of nearly 30 runs.

I think I made you wander too long in the dark by giving just a few top-ten tables. Here's a spreadsheet with all the players that made my cut of 300 bad pitches seen.


  1. Very interesting stuff! I would suggest looking at it as swings-at-bad-pitches per-pitch-seen rather than per-bad-pitch-seen, since free swingers do not get as many good pitches to see as hitters known for their patience. For example, no pitcher in the league is going to throw Bobby Abreu a slider in the dirt first pitch since he is known for being especially picky about first pitches, but you'd have to be insane to throw a grooved fastball to Vlad to start an at-bat. Laying off the slider in the dirt doesn't just make you one ball closer to a walk, it makes you that much more likely to see a good pitch.

  2. Max, are you adjusting the strike zone for the player's height? IOW, in order to figure out if a pitch is normally called a strike 10% or less, are you using each batter's "custom" strike zone (for his height)? If not, then you will get lots of swings from tall players on pitches you classify as bad, no?


  3. MGL, yes, forgot to mention.
    I normalized the strike zones before going into the whole process.

  4. Jake, you have given me an idea...