This morning I said my gut feeling was that the Twins would let Blackburn make one more start, but they weren't willing to wait that long. They've optioned the right-hander - who has this year and next year remaining on his 4-year, $14 million deal - to Rochester, and replaced him with relief pitcher Casey Fien.
We don't need to rehash Blackburn's struggles too much - the move was not unexpected, nor was it undeserved - but here's Fien's minor-league stats, from Baseball Reference:
In some ways, Fien is the consummate Triple-A pitcher - he's spent most of the last four years at that level, excepting his 14 major-league innings in 2009-2010 (in which he got bombed).
This means that, unless the Twins have some evil plan to convert Fien into a starter - something he didn't do regularly even back in his college days - one of the current bullpen staff will be making the transition to starting duty. Sunday's starter is TBA. (The way the bullpen has been pitching, maybe they should just let the bullpen start on Sunday.)
As for the 40-man roster, Fien's now on that list; the Twins still have one spot open on the 40-man.