Meh the part you are missing on is who the player IS.
Fans don't get to meet the players like GMs do, talk to their college coaches, etc.
Keim is right when he says that he missed more on the person than the player, but that can be said by most GMs.
I can excuse Jefferson because virtually nobody had him rated that high. It's somewhat tough because we had a guy on staff, a WR coach, who apparently openly told the staff he thought jefferson was the best WR in the draft but that doesn't mean even he knew how good he was going to be.
We didn't pick a WR IMO because we'd just made the D Hop trade so we figured we're set with Hop and Kirk and I would also somewhat assume they expected Isabella might develop although that seemed unlikely he just didn't show anything as a rookie.
But at the time there were lots of people on the board pushing Wirfs, there were people still wanting WR(like me) and there were lots of people who liked Simmons but as I said even then people weren't sure what position he was going to actually play.
No GM is infallible but when you miss repeatedly and the team ends up constantly having to play catchup as a result I think it is fair for fans to point that out.