[Wow, there is a ton of assumption in this post.
I would say a fair assumption from it is: the team is ready to take the next step now and dind't want to wait for Irvin to develop.
I could almost guarantee you that Pete and John don't look at one game, specifically a playoff game, as a rookie, and go "welp, he sucks. no redemption...get a rope." If they did, we'd have way more roster turnover than we have now. Now fans....we overreact exactly that much.
I also think the whole "Pete and John didn't want to spend all that money" on Bennett and Avril. They didn't effect our cap and we definately didn't over pay for them. I can just see the conversation "well, we drafted Irvin and he was raw, but after that Atlanta game....whooo boy. We don't really like Avril or Bennett, and good gosh we shouldn't be spending money on them, but after that one game...ouch !"
I try not to make all these sweeping assumptions. Sure, you're right....if someone was poor at a position, yes they get moved in an effort to salvage the player/draft pick. You see this the most with OT's going to OG (also the reason Tackle has more value...you can move a guy inside if he busts). Thing is, I agree somewhat...Pete and John probably didn't want to hinge our entire season on whether Irvin made that next step. Once they got Avril and Bennett, well now we're really deep there, so we move Irvin to another position. Not because he's irredeemable, but because he's an elite athlete and we want him on the field.