I see your point. One caveat about your theory, it assumes there is really only 1 player the team is targetting. If we have several WRs with similar grades then it makes a lot of sense to trade down because you can just look at a team's roster and see if they need WRs. Let's say we have 3 Wrs with similar grades and only 2 teams in the next 10 picks look like they might take a receiver: trade down 8-10 picks, pick up another pick and get one of your 3 guys. If however they are really only interested in 1 WR then I have no problem with them staying put, even if he is considered a "reach."