The first thing you have to do to beat man-up is to recognize it. That's pretty easy to do when sitting in the coaches boxes up high. It's also something the average fan doesn't do. Next time you're at a game, and it's third and long, stop watching the flow of the ball and open up your field of vision to watch all of the wideouts run their patterns. At the same time watch the defenders so you can start to recognize the coverage. As I've mentioned before, NU tends to run flood/vacate zone patterns which is fine against zone defenses, but pretty worthless against man to man. From what I have seen, this seems to be part of the problem.
The second thing is to recognize how the DBs are playing you. Are they in press or buffer? Third thing is, what is the individual DBs tendencies? Is he overly aggressive, playing very tight on short patterns and does he bite on the first deke, or is he more concerned with the deep ball, and give you a cushion. Does he have a weak side? How does he play a cross - does he switch or stay? Does he favor boundry or field coverage. How does he defend a down and out? How does he defend a curl, a fly? Can you get him on the wrong lead? Finally, your route has to be "crisp". If it's a down and out, the cut should be hard 90 degree at as close to full speed as you can go. Same for down and in and a "Z" out or in. If your defender is faster than you, you must get him to bite.
If you are a WR, or WR coach, these are some of the things you learn to look for. None of this is rocket science, and as I've said before, you don't have to be faster to get open, unless you're Willy Gault.