Seymour has a tougher assignment at RE than Warren does, since the best Guard and Tackle are on the QB's blind side. Also Seymour can play both sides plus NT, while Warren always seems to play only the left. Seymour can still push a double-team backward enough to get a hand on the QB, which obviously takes tremendous strength and skill. My guess is Seymour is border-line Pro Bowl starter and alternate.
Mankins is becoming dominant at LG, but he isn't a Pro Bowl starter yet.
Wilfork I forgot to mention - he is progressing very well and might make it as an alternate this season. Next season he could become a Pro Bowl starter.