As for the O-line against the Lions, they weren't doing any adjustments, they were not seeing the match up and changing the play, they just ran the play as is. I believe this was not an accident, it would have been different with a regular season game on the line. As for Mayo havn't watched much of him in the preseaon but the last few years he's been one of the few bright spots on the Pats defense and considered one of the best in the league and I expect a solid season out of him.
And pre season is a load of crock 90% of the time