You are ignoring his forced lay off from March 2009 until July 2010.
I'm really not. If I were ignoring that I would be much harsher. But a forced lay off doesn't take 3-4 mph off your fastball, which is the only way he could possibly have been considered a number one ML starter on "most teams" before this--it is way too hittable at this speed in the majors. And it's not like he never touched a baseball during that period, either--he had workouts and (presumably) kept in shape throughout that period, and if he didn't I don't see how he has anyone but himself to blame. Plus he's had a few months to work his way up here, including time at the instructional league--how is that so different from spring training? I'm not saying he isn't still a little rusty, but if he were really number one material I would expect a return more along the lines of that of Liriano or Volquez or Zimmermann--erratic performances mixed in with occasional dominance, and above all good stuff (even if it isn't getting hitters out). I don't see that with Maya.
Again, this isn't arguing that he's a bust or anything like that--it is way too early to say that--this is about him potentially being in the top 15 pitchers in the majors
(has to be a number one on "most teams"). Do you really believe we have to wait for a few more outings before concluding that he doesn't belong to that elite category? Here are the top 15 pitchers this year by WAR (and yes, they are all on different teams): Cliff Lee, Josh Johnson, Roy Halladay, Francisco Liriano, Felix Hernandez, Ubaldo Jimenez, Adam Wainright, Jon Lester, Jered Weaver, Justin Verlander, Zack Greinke, Tim Lincecum, Brett Myers, C.C. Sabathia, Gavin Floyd. I'm curious to know which of them you think Maya will be replacing in the near future.