This may be more than anyone cares to read on the subject, but I thought the Board post from earlier this afternoon re: Rodriguez wanting less fat on the lineman raised an interesting topic worthy of a serious response.
First, I think the poster was correct that Rodriguez wants lineman that do not carry much body fat. I recall last year in his first spring he said (paraphrasing) "by summer even the O-linemen will want to take their shirts off, which is unusual."
Second, I think the poster was also correct that his desire to have O-lineman without much "extra" body mass is atypical. Not, mind you, that other coaches want fat, fat, and more fat, or don't care about being in shape. But fat is still generally forgiven, and mass (in good, neutral, or bad forms) is still generally praised on the offensive line. When I played offensive line (~10 yrs ago) coaches at both the HS and college level definitely felt the more weight the better. Recall that the number of 300 lbers used to be a status symbol, and that good lines would be ogled for their average weight. (This is still largely true) Why does our coach depart from this?
I think Rodriguez wants leaner linemen because
a) they will be better conditioned, and have a lesser drop-off in form and concentration as games progress, and
b) they will be quicker, helping them to reach-block and sprint out to second and third-level defenders in the stretch zone blocking schemes his offense employs
There is always some concern that if you are too light you will be susceptible to the bull rush. Molk toes this line; sometimes teams can back him up a bit.
But from my perspective, offensive lineman don't usually get beat because they get pushed around--they get beat because they get run around. In other words, the typical lineman is a lumbering guy who can make a DB go splat if he can ever make square contact, and he can easily hold ground against a straight up bull rush; but the second level guy can usually dance around him, and occasionally a quick D-lineman will speed rush around him or a blitzer will shoot his gap before he can slide. I think Rodriguez' ideal lineman is a bit quicker for having less weight, and the idea is that his increased quickness will allow him to make contact at the second level more often and protect more lateral space at the line of scrimmage.
And I think Rodriguez has a great view on this. Let a leaner guy put his helmet (more often) on the linebacker or safety. Let him keep up with a speed rusher a little better.
The vulnerability--that an interior D-lineman will drive his man into the offensive backfield--is not as pronounced in Rodriguez' offense. His quarterbacks do not take a 5 or 7 step drop and can see a collapsing pocket happen more quickly. They frequently are delivering the ball quickly, and swinging it outside the tackle-to-tackle box. In short, the ball moves quickly, and often sideways, and this makes a well-formed pocket less critical. And on those quick lateral passes our smallish center is not merely excused for not holding the pocket--he's trying to sprint over to the sideline to find a linebacker flowing toward the play so he can put a facemask on his pads and sweep him out to the sideline. When we have 3 or 4 quick lineman getting over to that area of the field on those quick screens it will be a nightmare for defenses. I think RR has dreams of Barnum making it over from the opposite-side Guard position to blow up DBs on that play. (or maybe only I have them?) Losing weight and building lean muscle mass is definitely a key part of getting to the point where our lineman have the speed to "get in the way" of tacklers up field, across the field, etc.
If you want one clear example of what athletic, downfield blocking from O-lineman can do, watch McGuffie's screen pass TD v. Notre Dame. That's how it should work. In theory, of course, if you can suck in 4-5 pass rushers and deliver the ball properly, your screen gives you 9 blockers (11 - ball carrier and QB) against 6-7 tacklers. Why does 9 v. 6-7 not always deliver a TD? Because the big guys have a hard time getting to, and locking up, a target several yards down the field. It is tough. But when we are sending 9 athletic guys down the field on plays like that, well...it will be fun to watch. So; I for one hope we continue to slice fat from the line and recruit backfield burners.
On a final note, people have said that Rodriguez' kind of lineman is not an "NFL" type but I think in truth the NFL is moving more toward Omamehs than Borens. Certainly at Tackle. (This is especially true at left tackle, but notice that even if he plays RT scouts want to see Andre Smith cut his fat.) I think he is actually (rightly) selling both current and potential UM lineman on the notion that every year the NFL will want its lineman quicker and leaner. A big stomach is not a good thing, and I think is no longer even a neutral thing. I think our approach is forward-thinking and right on the money.
Seantrel, I hope you're reading--we'll have you burying guys 30 yards down the field, with a body you can take to the swimming pool.