Rosenthal's a groomed starter.
Sure, he kicked ass out of the pen last year, but he has a starter's arsenal and #1 ceiling. Let him start until he fails. DO NOT pigeonhole the guy into the closer role.
Besides, Carlos Martinez may or may not be able to handle a starters workload and has nastier stuff than Rosenthal even.
Cleto. Keep a very very close eye on Cleto. He can't be a starter; he's never figured out a passable 3rd pitch. However, he's slowly developed passable fastball command and it's a fastball that can be devastating.
There's a kid that you try to groom into a closer if for no other reason than he has no chance to succeed as a starter. He's clearly not ready yet, but he's built all the way up to a 3/1 K/BB ratio and a K rate well above a strikeout/inning. He's still extremely young and it wouldn't take much of a step forward in his age 24 season to be a truly outstanding bullpen weapon at age 25.
Motte wasn't able to establish himself in the bigs until 27 (obviously starting at catcher is why) and he's carved a nice career for himself. Time is still on Cleto's side and he's showing legitimate progress.
Don't sleep on the guy - he's not a write off by any means.
"Tact is the ability to tell someone to go to hell in such a way that they look forward to the trip"