From Brooks Baseball, here's a graph of Charlie Morton's fastball and sinker velocity throughout his career (I think that the June 2013 dot only includes one start, but his velocity was pretty similar in both of his starts so just roll with it).
It's well-known that Morton took something off of his fastball at the beginning of the 2011 season as he shifted to more of a groundball approach and put the focus on his sinker/two-seamer, but look at the way that his velocity declined all through that 2011 season and the way that it's bounced back this year (in what is an admittedly small sample of two starts).
What confused me about Morton's transformation in 2011 was why he'd abandoned his hard fastball entirely; it's one thing to accept that you can throw a sinking 92 mph fastball with more control and better results than a straighter 96 mph fastball, but that doesn't stop a 96 mph fastball from being a weapon. It seemed like Morton hardly ever used it once he transitioned to the sinker. Now there's a pretty decent explanation: his elbow started falling apart during the 2011 season.
I think that this graph is interesting, too:
Even with his velocity back closer to 2010 levels, there's a lot more movement on his fastball and sinker than there was in that disastrous season. Basically, Morton's throwing his fastball and sinker with the movement that he learned to generate in the off-season between 2010 and 2011, but he's doing it with the same velocity that he had early in his career.
It's obviously very early in Morton's comeback, and that makes it dangerous to read too much into anything that happens. These first two starts have been awfully encouraging, though, and I'm interested to see where Morton goes from here.
