The guts of Greinke's streak
Quite a few things have been different for Greinke. Greinke is hardly walking anyone, yet only 42% of his pitches are being registered as in the strike zone. Part of the reason he is avoiding the free pass is thanks to an impressive 64% first pitch strike rate. Throw in a decreased contact rate, and it's pretty clear that Greinke has good stuff.
The most notable change in pitch usage has been the increased presence of Greinke's curveball. Since 2007, his curve has went from 8% usage to 14% to 18%. Along with a slider and change-up, Greinke has scaled down his fastball usage. Intriguingly, his fastball has seen an improvement in horizontal movement since doing so, gaining almost an entire inch of movement inwards to righties. Greinke's curve has a violent break and his ability to control the speed of it is quite impressive. It's been measured as low as 60 MPH and as high as 85.
Give Dayton Moore some points for getting Greinke signed to an extension last off-season.