Well, the manager said it was just normal dead-arm. Which sounds a lot better than an actual injury, but usually dead arm is something you pitch through in the middle of the season, which isn't really possible here. Given what Suarez has gone through over the past two years he may just be coming up against his limit, as the article also notes.
Or it could be nothing. Or what you said.
Also, the story says we're not going to have a 5th starter the rest of the season, just bullpen games, though that would be no less true if Moore or Velasquez or Falter was actually the "starter."