Obviously not updated for the most current game (and I don't know how many sacks JT gave up to the Ravens) but the only place I could find with a "sacks allowed" stat says Joe Thomas only gave up one sack in weeks one through nine:
https://en.wikipedia.org/wiki/Joe_Th...eer_statistics
However, through weeks one through nine, Joe Thomas has lost seven overall points (97->90). Maybe you have some different stats you can provide? Wikipedia is obviously not the most reliable of places but it's the only thing I can find with player-specific sacks allowed, not just team-specific.
I can't see one sack allowed all year warranting a 7 point drop in overall (minus the Ravens game, as I don't know how many sacks he gave up that game, plus his overall from week 9 to week 10 didn't change). If you have any specific numbers for why Joe's been dropped or a more reliable source of sacks/pressures allowed then feel free to post, definitely not claiming Wikipedia as the gold standard.
I also noticed Joe's run blocking has dropped 11 points (93->82), on the NFL website it says the Browns average 4.7 yards per rush (good for 6th in the league) which seems pretty good to me, however they only average 99ypg (22nd) and only have 8 touchdowns (t-14th) so maybe that has something to do with it.
I'll admit I don't watch every Browns' game but seeing Joe Thomas suddenly drop from best in the league pass blocking (98) and third best run blocking (92) to having only 91 pass blocking and 82 running blocking (13th best) is odd imo.