Some of you people are downright ridiculous and you don't have a clue as to what you're talking about. Sorry to be so harsh but if the shoe fits wear it.
There is nothing to get all in a wad about either fracture. If it takes a MR to visualize a fracture then 1) it probably doesn't mean a lot 2) it likely didn't show up on an xray and/or xrays weren't indicated for the injury. It generally takes awhile for a stress fracture to show up on xrays and/or special techniques.
If Ware or Barber were at high risk to convert the fracture then they wouldn't allow them to play. Almost all stress fractures when initially diagnosed in someone who has minimal symptoms has a xray diagnosis with little clinical correlation for pathology now or for worsening pathology or a true clinical diagnosed injury in the future.
Those people taking care of these fine tuned and multimillion dollar paid athletes are themselves high paid professionals with their licences on the line. Without knowing a single one of them I'd bet all my money now and the future on them knowing their job and doing it well.
Take a chill pill and call me in the morning.