Snell has been diagnosed with golfer's elbow. He should miss no more than one start.
Dumatrait has bursitis in his rotator cuff, no structural damage. He should return for July 5th.
The next question is, who starts in the meantime? JVB is next in line for yet another shot, however he reported some arm stiffness in the last week. My guess is to watch Burnett in Indy to see if they try to "stretch him out" for a possible return to the rotation. Huntington did mention looking at other options, possibly a trade or waiver wire pickup. Basically, he will be looking to the scrap heap for help.
Hopefully the inflammation both are experiencing will subside and not become a recurring issue. The bad thing, speaking from experience, about having inflammation in your throwing arm is trying to compensate around the pain potentially causing more severe issues. Fantasy owners and fans of the Pirates should watch both pitchers closely upon their return, additional problems could arise for both.
Huntington needs to pick up some legitimate options somehow in the event one or both end up worsening their injuries trying to play through the pain. This is where Indy is the most important to the team and no one is performing well in their rotation.