assuming this is normal 12 team league dropping Escobar is fine if your DL slot is filled. Masterson won't be in the rotation for long this season, and probably is either traded or moved to the bullpen after this year. But streaming a Red Sox starter is never bad. Long term Masterson really just projects as a good number 3 in a rotation. A lot of value if he gets a shot with the Sox, a lot less value for most other teams. A move to the bullpen makes him worthless unless you are in a holds league, as Papelbon isn't going anywhere.
Don't drop Franklin for Chris Perez in any yearly league. Perez will close down the line, but his control was extremely erratic in the minors and he walked way too many guys. He won't be closing this season. Snatch him up in long term leagues though (if you are in a long term league I don't think Franklin is the player to drop for Perez though).