Okung was an upgrade but it wasnt apparent when it happened since they gave the Chargers a fail for signing him,... but making the probowl isnt being average. There are 32 starting LTs. And i can keep going, i just used two examples. There are more. Like I said, they cant and dont figure in the human element. Those grades dont account for somebody playing injured for one thing.
I know PFF for many is the bible to stats and players but stats are always an overrated thing and again, PFF has some useless stats IMO.