LT's need the anchor against the bull rush. I would doubt if there is a LT in the NFL who weighs under 320 and that would likely be a stretch. DL can get away with being a bit leaner and use more quickness. Its just really tough for a LT to be light. If you are a drive blocking guard you can weigh 295. The lateral movement and then anchor isn't necessary for guards. Tackles...especially Left tackles are best off being massive. Its the reason I wanted Sherrod to find his footwork so badly. He had the body for it. Even Bacteria is slightly undersized for the position.