Whew! If it is the hammy, in ANY shape, I like that better than an ACL.
Hammys are probablly the most common injuries in training camps as guys are getting back into shape and using those muscles in ways they haven't in a while, etc, etc.
From what I have observed over the years, the key with anything less than a true completely torn hamstring is how the medical staff treats it. It can't be rushed, yet the players need to be out there so they push and sometimes have setbacks. I think it was about 3 seasons ago that a rash of high profile WRs had this issue in camp. Hopefully the team will be smart and play it right.
I would guess that if its pretty significant, by the time you account for time lost and rest needed and all, this could be something that keeps Moreno out for the first week or two of the season but I definitely wouldn't expect him to miss the first 6 weeks or anything. And, of course, if it is THAT significant, we will know because the Broncos would likely put him on the pup.