You could, or you could lose out on the guy you really want and need. I just think that the drafting and scouting process is far from an exact science, so to say this guy should be drafted between 16 and 24, so I won't take him at 13....just seems silly to me. If a guy has a first round grade, and he fills a need....then I think you take him. Unless there is another guy that you have rated way higher.
Only time I would trade back, is if there are several guys still on the board that all have equal rankings on your board. At that point you can risk it. If Milliner is gone though, and Rhodes is the only other CB you have a 1st round grade one...then in my mind you don't screw around, you just take him.
GM's talk all the time. They all have a pretty good idea, who the other guy is selecting. So if you have an opportunity to get an extra pick, why not.