Has Brandon Mebane struggled to transition to the three tech? That is something I will explore deeper this week, but if he hasn't struggled, nor has he proven himself the force he was at the one tech.
Seattle has three players that are nominal three techs: Mebane, Cory Redding and Craig Terrill. Redding plays end, but is very much more a 3-4 end than a traditional 4-3 end. He influences and collapses the pocket rather than disengages and makes plays. He just isn't quick enough to edge rush and though he has been good and great at what he does, he hasn't provided much pass rush. Terrill is the standard organizational soldier type that is in turns under- and overappreciated. Seattle could upgrade but does not have to upgrade.
It has two one-tech types: Colin Cole and Red Bryant. Cole is the most reliable of the two and one of the most active tackles in Seattle's rotation. He can square against most single blocks, but that's his skill set almost in its entirety. Three tech used to be the feature tackle position in a 4-3, but the proliferation of 3-4 schemes has made the nose position in demand and three tech types less popular.
Signing Cole was a mistake. He hasn't proven much as a Seahawk and his ridiculous contract practically forces Seattle to start him. When Seattle needed its front four to provide pressure, it was exposed. Seattle's ends are average. Lawrence Jackson is developing, but is unlikely to ever be a great pass rusher. Darryl Tapp is a good speed rusher, but aside Cole, he isn't getting the one-on-one matchups he thrives against. Patrick Kerney still has burst around the edge, but his spate of injuries have sapped his upper body strength and he is as much a situational pass rusher now as Nick Reed. It's a nice foundation, but it won't strike fear into this season's opponents.
Seattle had a better front four last season, even minus Kerney. Mebane was a better one-tech than Cole, and though Rocky Bernard had little left to give, Mebane and Bernard were better collectively than Mebane and Cole. Mebane is supposed to be making plays and Cole stuffing tacklers, but Cole can't and so Mebane is again doing both. Bane does not get off blocks exceptionally well and his pass rush arsenal isn't developed. He established himself in this league as the type of punishing bull rusher that two blockers struggled to stop.
Anatomically, it's easy to see why: Mebane has an exceptionally low center of gravity, gets lower in his stance than almost anyone and erupts off the snap with such violence that many blockers are beat before they can defend themselves. As a three, a popular way of combating Mebane's explosiveness and exceptional leverage is to fade and draw his weight from over his feet. He gets ahead of himself, so to speak, and can be blocked whence unbalanced.
My notes on Mebane are mostly positive. He ran through a pulling blocker and tackled Beanie Wells for a loss of four at the start of the Cardinals second drive. He then played nose twice in a three man rush and performed ably, but wasn't able to separate. That's the problem for Brandon: He is great off the snap, but he does not consistently separate from blockers. As a one tech, Mebane was able to collapse the pocket into the quarterback and bull rush into sacks. As a three tech, he needs to be able to fight off a single block and show quickness to the ball carrier. That might not be within Mebane's ability.