The back and forth here about players unlikely to make a big difference in our scheme (any WR below #3 on the depth chart) is important because of a cautionary tale on our own team that happened in the not too distant past.
Once upon a time, Packer fans felt very satisfied that we had a sparkling WR corps, headed by Javon Walker and Donald Driver. Then, greed and the injury bug hit and our WR corps was troubled for an extended period. The laundry list of players who did not pan out further down the depth chart only accented why working hard at developing those guys is of critical importance. On paper, Nelson, Cobb and Adams look really good, and provided they stay healthy, they are good.
However, this is the NFL, and good top end depth can disappear in a heartbeat. We don't have good TE's with versatility to augment the WR position. Jermichael Finley, for all his consistency issues, could be deployed like a WR. In the same vein, there are RBs who can split out at WR within a scheme too, although we don't have one of those (Darren Sproles comes to mind. Buffalo and KC both had recent RBs drafted as much for their ability to split into space in passing roles as their wont to hit holes between the tackles).
As much as I'd like to see our top needs all struck firmly on the head by draft picks, TT understands that with this being a passing league, you can't stop adding potential to the mix to drive competition at a position that has as much to do with offensive potency in the current NFL landscape as any (with the exception of QB). Montgomery's arrival means developing players (see Janis, Abbrederis) are on notice. He's weak on the hands at the moment, but he gives us scheme flexibility (both he and Cobb can run it as well as catch it) and options for ST they don't. The options for both of these guys, given that they were selected through less costly means than Montgomery's 3rd round price tag, are to pack it in, or game on and get better consistently. Neither of them is Robert Ferguson whose 2nd round draft status bought him an extended period to develop.
It seems to me that our success at the WR position has a lot to do with the overall level of competition. Even Adams, a recent high pick, had to unseat a player who had done enough to earn the 3rd receiver role with some clutch play. Nelson and Cobb aren't facing job loss because they produce at a top flite level. So long as they do, they're starting for us.
In any case, I think what bears watching here is who rises to the top. I know if I'm a bubble WR and the prize is a chance to catch balls in games that mean something from arguably the best QB in football for a team that could win it all, every rep is like my last chance. Here's hoping Janis and Abbrederis are wired that way...