I think he's way overrated. I own him in one of my dynasty leagues, so I watched him a lot last year. There were plenty of scary moments where McGahee got banged up and limped off the field. He usually returned, but it seemed like he was getting injured every game.
Then consider that this is a guy that is going to be playing in an offense with a first year starter and 2nd year pro at quarterback.
Then consider that his offensive line lost its best lineman in Jonas Jennings.
Then when you go back and look at his numbers from last year, you'll see that of his seven 100 yard games, they came against teams ranked 31st(MIA), 27th(ARI), 5th(NYJ), 29th(STL), 23rd(SEA), 32nd(CLE) and 20th(SF) against the run.
I think McGahee is a talent and I think he has a good shot at a decent season. But he carries a lot of risk, and I think his upside is much lower than the average person.
I just don't think you can draft McGahee at #5. I think he's the most overrated RB on the board in redraft leagues.