From what I'm understanding, the Pats use bigger OLBs than most schemes, and Matthews was too small to set the edge against the run. Is this correct?
I'm not an expert on variations of the 3-4 scheme and how BB's approach differs from others. Perhaps someone like Jays52 or Bakes781 could discuss that. But as I understand it, BB looks for some of the following form his OLBs:
1. They have to be able to read the play and diagnose run vs. pass. They aren't primarily just pass rushers. As DaBruinz noted last offseason when we discussed this topic, "the primary job of the OLB is to diagnose what the play is. The OLB has to be able to discern between a run and pass play. Once he has done that, he has to be able to set the edge on a run play on a rushing play to his side. Or, if its a passing play, rush the passer where someone else picks up the TE and or the RB, or drop back into coverage himself if one of the other line backers is taking up the rush. The Patriots, under Belichick in the 3-4, have never had an OLB JUST put his ears back and rush the Passer on every down."
http://www.patsfans.com/new-england-patriots/messageboard/13/223412-our-1-need-mile.html (post #31)
BB demands more "read and react" skills from his OLBs than do some other 3-4 schemes, such as those run by Dallas and San Diego, where the OLB is primarily a pass rusher, or even Pittsburgh where the LBs tend to be disruptors rather than reading plays and reacting.
2. BB sets a huge amount of value on the OLB being able to "set the edge" in a run play. This requires the OLB to function like a lineman and take on blockers. The LBs aren't so much protected by linemen (the way they are in Baltimore's scheme, for example), they function almost like linemen in taking on blockers and disengaging from them. This in turn generally requires a bigger and more physical OLB than, for example, speed rushers such as Elvis Dumervil and James Harrison, and puts a premium on skills like stacking and shedding. This is particular true for the "strongside" OLB, which Mike Vrabel played. The "weakside" OLB (played by Roosevelt Colvin and later Adalius Thomas) doesn't have quite as much focus on taking on linemen and is a bit more free to pass rush, but still BB places a relatively high value on setting the edge and containing running plays. This disfavors OLBs who are too slight to take on blockers and set the edge, and OLBs who stylistically tend to run around blockers to make the tackle. Matthews had this reputation coming out of USC.
3. BB uses his OLBs in coverage more than teams such as Dallas and San Diego, so finding players with coverage skills is a plus. That was one of the major factors in targeting a guy like Adalius Thomas in FA. This might have been a question mark for guys like Larry English who were more DE's who rushed the passer all the time. Matthews had superb cover skills, having started as a safety at USC.
4. BB tends to require a lot of discipline from his players. He places a premium on players sticking to their assigned area/responsibility and the defense functioning as whole, and disfavors players who tend to freelance a lot.
5. BB places a lot of value on height in his OLBs, and particularly likes tall players with long arms who can get their arms up and clog the passing lanes.
BB doesn't seem to particularly place a lot of value on stats like sacks. Only once in 10 years have we had a LB get more than 10 sacks (12.5 from Vrabel in 2007, when we were ahead a lot and could rush the passer more), and only 3 LBs have had as many as 8 sacks in the past decade (Vrabel, Colvin and McGinest). He wants OLBs who can do a variety of things well and have the discipline to do their job so that the whole defense functions the way he wants it to. The Pats 3-4 OLB is a less glamorous position than that on Pittsburgh, San Diego, or Dallas, for example. It's a blue collar job.
My impression of Matthews is that he is a heat seeking missile who is great rushing the passer and running around blockers to make tackles, and great dropping into coverage, but that he may lack the discipline to fit into BB's scheme, some of the height that BB likes, and some of the bulk and physicality to take on blockers and set the edge the way BB likes. That's not meant as a criticism of Matthews, who is turning out to be a fabulous player, more a comment on how he fits to BB's scheme. Whether BB should be more flexible in the type of players he targets is a whole different issue.
For all of those clamoring now that we should have taken Matthews, note that last spring almost 75% of those polled on this board preferred Larry English at 3-4 OLB for the Pats. English currently has 2 sacks as a backup at San Diego, but could very possibly take over next year as the starter for Shawne Merriman.
http://www.patsfans.com/new-england.../13/224567-larry-english-clay-matthews.html
I'll defer to my more learned colleagues if they disagree with any of the above. I'm not a schematic analyst by any means.