I expect there will be a lot more TE pass-blocking after the half, and likely some plays with a 6th lineman in at TE. The lack of functional pass-protection, especially with McKinnon being a liability just due to size and him being made out of cardboard and held together with hope... it's no wonder Mullens is struggling. If Garapollo was in during this game, I imagine he'd have gone down in a way that scares the fans at home at least once by now, so there's a blessing in that. But something is up with the line, and Williams isn't out there playing like top tackle in the league at all.
And that's rough because that takes Kittle out of some plays where he's arguably the most effective deep threat on the team by a mile.
Adjustments gotta be made, because Mullens isn't actually doing badly. The offense rolls when the passes can get off, and outside of the boneheaded INT - reminiscent of the other QB - he's been good when he's not being mauled.