I don't think Koppen is too small, you don't need to be a huge guy to play center in the NFL.
The Patriots just need to run the ball more and run it more effectively. One of Bill Walsh's philosophies was a team could often be judged by how well it rushed the passer/played defense in the 4th quarter.
Why?
It's a lot easier for your offensive linemen when the opposing D has been on the field a lot and are gassed and have nothing left in the 4th quarter. When you don't convert your 3rd downs on offense, you give the enemy D a chance to rest, to recover and to be fresh for the 4th quarter.
There are a finite amount of snaps a defensive player, esp DL, should take to stay effective. Once you go over that number, you are gassing the player out. Same on O line. You gas your O line the more you expose them to a fresh rotating D that has time to rest and recover. The more snaps you play under that condition, the more it taxes you.
Every O linemen is too small, too slow, too ineffective when they start out poorly and have to play from behind and have to continually take on a fresh defense. This is one of the limitations of losing the fullback position, someone to punish the defense again and again and hit them hard and make them pay on every snap. Moose Johnstone used to beat the hell out of other players. Tom Rathman too. Brad Muster. William Floyd. Made the O lines job a lot easier. Tough to man handle that O line when you keep getting punched in the mouth by the full back.
Do the Pats need more talent on O line? Absolutely. But a little smash mouth football goes a long way. If people want to count something, don't do Koppen's size alone, count the number of snaps in specific conditions.
