Tim Lincecum's New Slider
First off congratulations to the Giants on their first World Series title since moving to San Francisco, and first title in 56 years. They played very good baseball since September 1st in order to pass the Padres to get into the playoffs, and then beat the Braves, Phillies and Rangers once they got there. One of the keys was, of course, very good pitching from their two top pitchers, Matt Cain and Tim Lincecum. I wrote about Matt Cain throwing lots of change ups over at FanGraphs, and interestingly Tim Lincecum has also drastically changed his pitch usage in the past couple months.
Lincecum's pitch usage shift went more noticed in the media, with reports that he had changed the grip on his slider and was throwing it more. Classifying Lincecum's pitches from the pitchf/x data is not as easy as some other pitchers from; particularly troublesome is differentiating his slider and his change up. Here is one example game where you can see how closely they cluster. I think the best way to tell the pitches apart is to look at the spin direction and speed of each pitch. Here is a polar plot comparing these two values with the different pitch types color coded.
At least one report claimed that Lincecum changed his grip on September 12th, so I wanted to see whether his slider was any different since then. Here I plot the spin and speed of his slider, this time on a rectangular, non-polar plot. Sliders since September 12th are circled.
In Lincecum's two Cy Young years, 2008 and 2009, he complemented his great fastball with a with a mix of about 15% curves and 20% change ups and under 5% sliders. Up until September of this year his pitch selection was similar. But since early September he has embraced his slider and thrown it often (18% of the time). That culminated in the last game of the season when he threw it 40% of the time. It will be interesting to see how he decides to pitch next year having established multiple excellent secondary pitches.