Can he keep this up? Is there any precedent for his meteoric rise?
If there is a precedent for his 2012 season, I can’t think of it. The Orioles signed Miguel Gonzalez as a minor-league free agent in spring training based on his impressive work in winter ball. Since he didn’t have the benefit of a full spring training, the Orioles assigned him to the Norfolk bullpen, where he pitched impressively. Then, they stretched him out as a starting pitcher, and he continued to pitch impressively. Recalled to Baltimore, he pitched impressively in the starting rotation during the Orioles’ playoff run.
Because I can’t remember anything like this, there’s no obvious comparison. Looking back at Gonzalez’ career, it’s even more unexpected. He was originally with the Angels and pitched fairly well; spent all of 2008 on the Disabled List, was selected in the minor-league Rule 5 draft by the Red Sox and spent all of 2009 on the Disabled List. He pitched reasonably well in 2010 but poorly in 2011; the Red Sox released him. Then the Orioles signed him and his career took off.
The only relevant thing I can think of is that he missed two full seasons with an injury, and he pitched substantially more in 2012 than he had since 2007. As a result, he may be more of an injury risk than normal. It’s likely that he’ll be asked to up his innings to the 175 level or so, which may put more stress on his arm. I don’t think he’ll be as good in 2013 as he was in 2012; but even if his ERA goes up by half a run, it’ll still be at 3.75, which is fine. I don’t see any reason to think that his 2012 was a completely unsustainable fluke, but forgive me if I want to see him do it again.