I like Nolen, and if they think he's the best DT available at 12 I'd be happy to take him. DT is my #1 target to improve this defense and team.
And even though I do generally agree with BPA, I would never fail to draft a difference maker for your team, just because his "perceived value" isn't quite where some people say it should be. That's just a bad draft strategy IMHO. You draft the best players you can, at the positions your team needs the most help and you make your team better. Regardless if he's ranked or "projected" to go 20 picks later than that.
That's the entire point of the draft, to make your team better, more complete and more competitive.
You can't do that taking a higher "ranked" player, (for example, taking a TE who is a good player, maybe as good or better than your current TE, but when using him he doesn't make your team very much better than it already is) vs. taking a good player, at a position your team really needs to upgrade. Upgrading the weakest part of your team will always make your team better than adding a good player where he's not needed.
Now I say all that but add ***Within reason! You should pass on a generational talent, unless you get extremely well compensated to trade out. Nor do you don't take an average player over a great one just because of need either. It has to be reasonable.