Jeff Passan at Yahoo Sports has a great post up entitled, "25 things you didn't know about baseball". It's a great post of surprising stats he has uncovered at FanGraphs.
There are two Twins mentioned in his post, the first is #9, tonight's starter Francisco Liriano. Apparently the stats show that his slider is just fine, but his fastball sucks. It sounded like he was having trouble locating it tonight, so that actually makes some sense, but it's not what I've been hearing from the experts.
The 2nd Twins player is Joe Mauer, who is one of 6 players who does not have a weakness at the plate. Yawn. That's about as surprising as Sid Hartman referring to someone as a close personal friend.
Read the whole post. There's some interesting stuff in there. My only question would be about giving an individual pitch an ERA. I would put forth that pitchers use some pitches to set up other pitches. They have their strike out pitch, but it's only good if its used in the right way. From what I can tell, they are only taking into account what the count is, and not what type of pitch preceded it. As a former catcher, this seems incredibly important to me. By changing speeds, eye level, location, etc. the pitch sequence matters, not just the pitch selection.