Not only that, but I think that college spread offenses really reduce the necessity for a top tackle.
A decade ago you could've named five or six elite tackles in the NFL, almost off the top of your head. Now? After Thomas and Long, you really have to lower the bar to include another guy.
Maybe it's a generational thing--there are a lot of young/unproven OTs in the NFL right now--but it seems like they just don't make 'em like they used to.
I think you're right on the money with this. With the spread offenses the offensive lines don't really have to be serious pass blockers. All they have to do is hold the rushers off for a second or two. Meanwhile the pass rushers are under tremendous pressure to get to the QB ASAP on twice as many plays as their ancestors were.
Pass rushers get better and Offensive linemen get lazy?