I don't know what to do. Most of the roster well below career norms and it would be extremely unlikely for this to continue.
Masterson and Kelly worry me the most. Kelly was looked at as bullpen guy most of his career due to a lack of a serviceable 3rd pitch and his command issues. Masterson doesn't have the velocity anymore to fool the lineup more than a couple times, max, and has the same aforementioned control problems that stem from his side-armed delivery. If he can't regain his velocity in the BP, he's truly a ROOGY at best.
Porcello will be fine, I think Miley will settle down as well.
Peripherally Buchholz is an enigma, he's like an injury prone version Javier Vazquez, who managed to consistently under-perform due to his mental fragility. He might rebound, might suck.
They could call up somebody, but there's likely going to be growing pains that are most likely to produce the same lackluster results we're seeing right now.
What to do about the offense? Wait and see, besides getting rid of the trash. (Craig, Victorino, Nava?) Castillo should provide a boost when he's going at full speed, and Swihart is likely to make an adjustment going forward.
Expectations have to be realistic. On paper, most saw this team as having a mediocre rotation and a good offense; maybe a shot of 90+ wins if everything banked right. Obviously this isn't the case and It's really not worth tampering with the development of minor leaguers in order to try to patch together a sinking ship. You can hope that things settle down and they play .500+ ball from here on out, but the talent level just doesn't look good enough to compete with the rest of the division & AL.