The bold comment is what peaked my interest in their grading system. While I never played anywhere on the OL, I was at enough practices to hear many coaches preach to the OT's to get back quickly and force the DE's around the back side of the QB...
This is why so many OT's in today's game use that goofy leg kick to get back as quickly as possible!
This is also why QB's are suppose to step up in the pocket!
From everything I've read about PFF's OL grading system when the DE or any defensive player crosses the line of scrimmage & if PFF decides that you are suppose to block him, it is a "Pressure"... They don't have any clue what the actual blocking assignments are... They also don't take into account whether or not a QB holds onto the ball to long... On some plays the OL is suppose to let the defenders come forward...
Because they don't know what all of the variables are on each play, it is a flawed system!