I think the Cheese's third point is the main one.
• Last year, we had BBs who were capable of getting 3 - 6 ypc and broke one regularly. Result: the MLBs couldn't break for the edge as quickly and the block on them was easier.
• Last year, our main ABs could block. Period.
• Last year, our ABs were bigger, stronger, and faster. And more experienced. Result: the O ran a lot faster and it was easier for the OL to sustain a block.
• Last year, because our BBs were so effective and the edge game was so dangerous, Ds had to play it safe and react. If they didn't the phrase, "live by the blitz, die by the blitz" would take on a whole new meaning. Result: it's a lot easier to pass block.
So, in short, I think the OL is about the same - though losing Shaq hurt - but the O execution and effectiveness is a lot less. That means Ds can lay their ears back with less fear of the big run. If we started to hit 20+ yard runs regularly, I can guarantee that the blocking would pick up. To last year's level? Ah, mem-sahib, that is another story.