Thoughts on Chris Sale
I've seen it mentioned in a few places that Sale was a reliever converted to starting, with some people worrying that background could lead to durability problems. That's a misunderstanding that needs to be cleared up.
It is true that Sale began his professional career as a relief pitcher and was used that way in the majors in 2011. He also pitched out of the bullpen at Florida Gulf Coast University as a freshman in '08 (36 innings, 3.47 ERA, 43/10 K/BB) but that is hardly unusual for a freshman and he moved into the rotation for 2009.
He handled it well, pitching 89 innings over 12 starts with a 104/27 K/BB and a 2.72 ERA. As a junior in 2010 he went 11-0, 2.01 in 15 starts with a 146/14 K/BB in 103 innings, which earned him a spot in the first round, 13th overall.
The Sox brought him to the majors as a reliever very quickly that summer, but that was primarily to break him in and keep his innings count at a reasonable level as he adjusted to pro ball. He was mainly a starting pitcher as an amateur, and was seen as a future starter by most scouts when he was drafted.
Sale has the risks associated with any young pitcher. If you want to worry about his funky delivery and skinny frame, that's fine, and one can certainly argue the wisdom of the contract. However, extra concern about him being a "relief pitcher converted to starting" isn't necessary. I don't think that is an additional risk factor in his case.