Why Did Colon Sour as Summer Turned to Fall?

One site I have long been a fan of is BrooksBaseball which has a lot of pitch f/x data, basically an encyclopedia of every MLB pitch thrown the past few seasons. They now have a new feature called "player cards" which basically gives you an entire database on any given pitcher. You can mess around with it and see for yourself how neat a resource it is. I still am familiarizing myself with some of the data they have and how it can be of utility to discovering things about our pitchers, so I decided to take a gander at some stats for new Athletic Bartolo Colon.

The line on Colon from people who argued against his signing was how he faded down the stretch. Indeed, Colon did fade down the stretch as this chart of results adeptly proves:

The ERA climbed steadily from June through the end of the year, while the FIP still rose but not with such a clear upwards trajectory. Many people said that Colon lost something off of his fastball by the end of the year, but aside from April and September his fastball seemed to be a relatively consistent 93-94 mph, not the big drop off one would assume might accompany such a significant results difference. His sinker too which was consistent at about 91.5 mph all season long fell about a mile as well come September.

But what was different aside from the speed? What I found interesting is how often he used the pitches changed dramatically as he began hitting a blip in the road. Typically he used the fastball and sinker in the mid-80% range but then come July and August that shifted. August in particular is a noteworthy month, because he used his sinker relatively-sparingly compared to months previous.

But also in that month of August we see what is most interesting of all. The fastball still moving and still being thrown at a relatively high clip, is now resulting in a lot of good solid contact. The line drive rate on balls in play for the fastball goes to a year high 28.57%. But when you actually break down that number, that is eight line drives for August. Pretty insignificant stuff right?

Furthermore the most noteworthy part of Colon's season is that his K/9 rate dropped precipitously from where he had been all year when the calendar turned to August. He had been all year long at 8.1 K/9, yet that figure from August 1st onward was just 6.0 K/9. The pitch f/x data shows a culprit, the percentage of whiffs to swings was significantly different for him on the sinker in August, and then the fastball come September.

What's interesting is there is the common belief that people reliant on the sinker, throw it better with a tired arm. I know I have heard Ray Fosse say this with respect to Trevor Cahill and I think I heard Tim McCarver say this once during the playoffs perhaps about Roy Halladay or some other sinker reliant pitcher. Does Colon's higher average sinker speed somehow demonstrate that that theory could be correct? The sinker was faster in August than in any other month, yet it fooled the fewest hitters by a long shot and guys had better contact on it than they had prior landing line drives with a greater frequency (though again those numbers are so tiny that they don't have much statistical value). September's lower fastball speed might indicate why so many fewer hitters we fooled by that pitch as the season neared its end.

The sinker is the pitch that Colon (or perhaps it was Russell Martin and Francisco Cervilli) had the most faith in. As in 3-2 counts he went to it 74% of the time. Could his abandoning the sinker in August have resulted partially in that month being such a mess? Then the return to using it in September somehow turned into it being tagged for line drives. The cool thing about Pitch f/x data is that we can make hypotheses like these and ask all these questions. The end result though is oftentimes it just leads us to inconclusive results as on a month to month basis there is little to be gleaned that is statistically significant. We do know that Colon labored through his last two months of baseball last year, it is unclear whether or not that will be the case again in 2012 for Oakland.

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