While developing a plus cut fastball has keyed some of John Danks' success, his changeup has become his go-to out-pitch.
Only one left-handed starter in baseball had a better-rated changeup than Danks in 2010—that being Jon Lester. Danks' changeup rated as 2.28 runs above average per 100 pitches, and coupled with a plus cutter Danks racked up a 4.3 WAR last season.
About 18 percent of Danks pitches were changeups last season, making it his third-most used pitch. He used it most frequently with two strikes: 15 percent on 0-2, 30 percent on 1-2, 42 percent on 2-2 and 34 percent on 3-2. Interestingly enough, though, all those percentages are lower or similar to his 2009 changeup percentages—in 2010, Danks threw a higher percentage of cutters with two strikes than the previous year.
But Danks did throw his changeup better in 2010 than 2009. It's a simple explanation why, too: better command.
Heat maps via FanGraphs
Danks was able to locate his changeup away from right-handers a lot better in 2010 than 2009. That's not to say his command in 2009 was bad—Danks still kept his changeup down and it still rated as a plus pitch. But that he was not only able to locate down but also away led to the pitch being an elite piece of his arsenal.