I'll look at Rodriguez' 2013 so far, comparing it to his 2012 struggles, along with his successful 2011 season, and his 2008 season with the Angels for further reference, a season, which by fWAR, he hasn't repeated since, in order to see if Rodriguez' good start is just a small sample size, or whether the data suggests that he has returned to form and become a valuable trade chip.
First, to get a look whether or not he has "changed" as a pitcher, here are Francisco Rodriguez' release points by season.
overrated in testing, and it is nearly impossible to look at release point consistency over a full season due to the difference in how it is measured from ballpark to ballpark, we can compare Rodriguez' 2012 and 2013 and see if he is being more consistent or less consistent
There is no real velocity difference from year to year, and other than his 2011 blip, he has located it glove side on average. So we don't really get any conclusive results here, so what about his changeup?
Just like the fastball, this is another pitch that has drifted glove side after originally being an arm side pitch. Just like the fastball, he is getting it more arm side this year. The velocity drop on the change has been more dramatic than the curveball, really mimicking the fastball.
By throwing less glove side this season, I do think there is some validity to Rodriguez' fast start. I do think he has some value out of the bullpen, but I don't think there is any reason to believe that he is 2008 Rodriguez, or even 2011 Rodriguez.