The two-seam (45.7%) and four-seam (35.9%) have been his main weapons, though he's thrown a few sliders (12.5%) and changeups (6%). Despite the 13 strikeouts, Colon's only garnered 13 swinging strikes - over 73 swings, that's a whiff rate of .178, which is below average. Despite the small sample size, here are the whiff rates for Colon's pitches so far:
The four-seam fastball has looked very good in the whiff department, but in two-strike counts, it's been the two-seamer that's been most reliable for Colon. A lot of his sinkers have been on the glove-side (inner to lefties, outer to righties) half of the plate, and he's been able to fool hitters with it in the strike zone with a watch rate of 50% (league average is around 37% for sinkers). Of his 13 strikeouts, six of them have come on the spill-over, the "Greg Maddux pitch." The graph below shows those six pitches (including some possibly generous calls), overlaid on an approximated strikezone. Also, you can watch these videos to see some of Colon's strikeouts this season.
Colon has shown impressive command over his first three appearances, and if he pitches well, I wouldn't be surprised to see him hang around the rotation for a while given Hughes's injury and Ivan Nova's ineffectiveness. I think the first big question is whether or not he will be able to hold up over a full start - questions about his durability were what landed him in the bullpen in the first place. Also, will the spill-over fastball lose effectiveness as hitters see it more? Will the free-swinging Blue Jays refuse to take it for a strike tonight? I guess we'll find out.