Personally I do think he is significantly better than those other two and worthy of a 1st round pick. Going back to his 2012 tape when he was healthy, Nix was the best player on one of the best defenses in college football, leading ND to a National Title game. He might not have gotten the same recognition as some of the other guys on his team (Te'o, Tuitt etc) but he was the most important player on that team. I've said previously I believe Nix is the best NT prospect since Ngata and I think he is a much better prospect coming out of college than guys like Poe and Phil Taylor.
The reason I rate Nix so highly is because I see him as much more than just a base NT to stuff the run. I don't care what the combine stats say because they don't test football applicable athleticism, especially for NT's, but Nix is very athletic for his size. He has really quick feet which allow him to keep his weight over his legs and gives him a strong center of gravity. He does a good job of getting initial penetration, and while he doesn't have the closing speed to put up big sack numbers what he will do is create pressure, force throws, draw holding calls and be a tfl machine against the run. But more importantly than that he will be a facilitator for his teammates. He will draw double teams and free up his fellow defensive lineman or linebackers to make plays, which won't show up in the box score but the impact will be immense. I believe the way Daniel Jeremiah describes him is "having the potential to be a 3 down difference maker in the NFL" and I certainly agree.
All throughout the draft process I have been going back and forth between Nix and Ra'Shede Hageman on who is my top DT. I think Nix is a top 10 talent and would have been regarded by many as the top DT in last years draft had he declared. Hageman is really intriguing because of his elite size, freakish explosion and athleticism and huge upside. In the end though after the moves the Pats have made I have finally decided Nix is my #1 DT in this draft.
With the moves we have made to solidify the secondary, hopefully we will be able to play a lot more single safety man to man coverage. To complement that, instead of looking to get a great pass rushing DT, what I would look to do is build a strong run defending defensive line. If we can stop the run with a strong front 4 and play single safety man to man coverage that really opens up a lot of options with our LBers. One thing we know BB puts a huge emphasis on is disguise, and having our LBers be able to play freely would certainly help that. That allows us to be a lot more exotic with our scheming and frees up Mayo, Hightower and Collins to blitz a lot more. While it is great to have individual talent to get after the QB, teams can always add resources to shut down certain players. When you can scheme to bring pressure from anywhere I think is much more effective. I still want a pass rushing DT that can beat his man in sub packages, but I still believe even in this passing league you have to stop the run first.