If I'm not mistaken, it was only after they got an MRI done that McIntosh's injury was detected. That (coupled with the fact that he's probably going to play this season) leads me to believe that it wasn't a serious enough injury to be detected at first. Rather, I'd applaud them for ordering the MRI and saving the team a $#!tpile of cash.
DB did come with a rep for lower leg injuries, but what were we going to do, hold him out of all training camp? Strains and tweaks are routine. Obviously, hindsight is 20-20, so if they could go back, they'd let him sit the whole week to be extra cautious. But Boston could have opted out of practice if he felt it was serious enough. Hell, where was his pain-in-the-butt trainer Chuck Poliquin?