The Angels project to have six starters for five spots by that point, establishing some semblance of depth for a rotation that has been decimated by injuries.
It also means someone will have to go.
"We've got a ways away before we're going to make a decision like that," Angels manager Mike Scioscia cautioned on Monday, before the start of a three-game series against the Astros at Minute Maid Park. "Let's just wait and see where Nick is, and then we'll have a decision based on our evaluation."
Angels starters have pitched better of late, giving up a combined three earned runs in 27 innings over the last four games entering Monday's game and lessening the urgency of Tropeano's return. Tropeano's injury was never considered serious, but the organization wants to be extra cautious with his shoulder because, as Scioscia said, "he has a history of it."
Upon return, Tropeano will be one of three healthy Angels starters who can be optioned to the Minor Leagues, along with Hector Santiago and Matt Shoemaker.
Sending a starter pitcher to Triple-A appears to be the more likely scenario, as opposed to moving one to the bullpen, because more than half the season remains and the Angels need to preserve as much starting-pitching depth as possible.
Tyler Skaggs, struggling to return from August 2014 Tommy John surgery, will pitch three innings in Arizona on Wednesday but still has several hurdles to clear. The same can be said for C.J. Wilson, who has battled shoulder issues since the start of Spring Training and still isn't ready to resume a rehab assignment. And Andrew Heaney and Garrett Richards are nursing tears in their ulnar collateral ligaments that may require Tommy John surgery.
Scioscia declined to state whether Tropeano's rotation spot is secure, saying: "We're not going to discuss anything like that. When the time comes, and there's some things to talk about, we will."
Alden Gonzalez has covered the Angels for MLB.com since 2012. Follow him on Twitter @Alden_Gonzalez and Facebook , and listen to his podcast. This story was not subject to the approval of Major League Baseball or its clubs.