Why is anyone surprised the OL is rated poorly in pass protection? I say again that is largely on McVay who abandons the run and allows the front 7 to simply play pass on every down. Overall the OL grades reflect a new OL in their first season together with a new OL coach. Getting basically a middle of the pack grade isn't a bad thing.
IMO their grading will improve next year as they learn to play together as a cohesive unit. Also, if McVay will return to his balanced run/pass attack. He will have Kyren and Royce as his #1  RBs. IMO they were graded lower in the run blocking because of how McVay kept playing the smurf who would go down with an arm tackle, while ignoring Freeman who got more yards with fewer carries. Now with Williams and Freeman the OL grading should improve in the run game.
That balance will improve their pass blocking as well. I see this unit as finishing rated between 14-16 which is a huge improvement for this rebuilt OL.
IMO the OL isn't the problem. It's the playcalling that is the problem. Where did the McVay of 2018 go?
If McVay insists upon slow developing pass routes he needs to give Stafford shorter quicker developing routes as well. He used to do that when he layered his route tree. Both Williams and Freeman are capable receivers along with the TEs. McVay needs to get them more involved in the passing attack. McVay needs to understand that moving the chains is not a bad thing. Limits, the opposition offensive possessions, keeps his defense fresh. It also protects the OL as it develops.