Jeremy Bonderman: Why the Struggles?

Everyone has their theory around why Jeremy Bonderman has struggled so mightily in this 2008 campaign. Everything from decreasing velocity, to diminishing stuff, to possible injuries. Speculation runs just as rampant as one of his 2-seamer's he's had so many problems controlling this year.

Well, here's what I've figured out about Bonderman: He's not using his slider nearly as much. Stunning analysis, Mike. No, really, that's hard hitting work, you should get paid to do this.

But, all kidding aside, he really has backed off the use of his slider. I've looked at the numbers via Josh Kalk's blog which has player cards (both hitters and pitchers, for 2007 and 2008) thanks to the publicly available Pitch f/x data that MLB Gameday uses.

Let's look at the numbers . . .

In 2007:
He threw his fastball 58.27% of the time, his slider 36.53%, and his change just 5.2% of the pitches that were recorded by Pitch f/x data.

This year, he's been recorded as throwing a fastball, a sinker, a slider, a curve, a splitter, a change, and a cutter. Most of these are probably just due to the classification of the pitch as sometimes he'll back off his slider a bit velocity-wise and it acts more like a curve.

So, I'll just group these into Fastball (add the sinker in there as that's his 2 seamer classified as a sinker), a slider (add the curve to the slider numbers), and a changeup (I'll add the splitter in there as it's probably his changeup just thrown harder or classified wrong depending on the velocity of the pitch).

So, in 2008:
Of the 660 pitches recorded by pitch f/x data, 448 have been fastballs (67.87%), 128 have been sliders (or breaking balls; 19.39%), 84 have been change ups (12.72%).

Now, he's always had a dynamite slider with great, late bite and not a ton of horizontal movement (probably 1 to 7 or 1 to 6:30 movement if you're looking from a centerfield camera at a clock face ... the downward bite is what makes it so lethal). But, he's dropped off the number of times in throwing it. He's actually throwing it 17.14% less this year than in 2007 (quick aside on the sample sizes: 2007 recorded 980 Bonderman pitches where as 2008 has already recorded 660 Bonderman pitches) . Now, the change up is being thrown 7.52% more than in 2007, but that still leaves a 9.62% drop that have become fastballs rather than a slider.

Now, the Hardball Times has Bonderman throwing a total of 12, 581 pitches from the start of 2004 through 2008, before tonight's start. In that time frame, he's pitched in 132 games, which is 95.31, or just 95 pitches per game.

So, we'll take his 95 pitch average for the last nearly 4 years and apply his 2007 percentages to them.

In 2007, his pitch breakdown would have been:
55 fastballs
35 sliders
5 change ups

Applying his 2008 percentages to his 95 pitchers per game average, they shake down like this:
65 fastballs
18 sliders (breaking balls)
12 change ups

So, he's throwing, on average, about 17 less sliders a game. That is 17 less times he's throwing his best pitch. Imagine Johan Santana throwing 17 less change ups, Dan Haren throwing 17 less splitters, Randy Johnson throwing 17 less of his devastating sliders per game. That's quite the discrepancy.

What's the cause of this? Well, he did have a bum elbow from (in my opinion) his 20th start of his 2007 season onward (July 29th, in Anaheim on Sunday Night Baseball where he blew up to the tune of 10 ER in 1.2 IP).

Is it an organizational demand that he throw less sliders and more 2-seamers? Is it something he's doing consciously to not put more strain on his elbow? I don't know, these are the questions that are tough to answer as an outsider.