It is a fair way to go - and the big arms in Round 5 to 10 are still being drafted as starters (every pitcher is drafted as a starter). But then you determine quickly - does the guy have the third pitch, can the guy hold his velocity. If the answer is no (the answer is usually no) - then to the bullpen, where you don't have to worry about things like that.
The Red Sox if they have erred, is taking high probability starters in those spots - you know, guys with command 88-92, know how to pitch. The ceiling is limited, and the bullpen utility becomes dicier. For a good reliever, you're looking at one or two wipeout pitches, and the other things (great control - still has to be acceptable, third pitch, turning lineup over) are less important.