Nothing wrong with Sturgis. He's not immune to normalcy. It's the same as our red zone percentage. That atypically hot start couldn't continue. I remember posting that we'd start settling for field goals and miss some of them. Same thing with kickoffs. As the season extends the kicker isn't going to nail everything deep into the end zone. That was Belichick's argument for moving the kickoff up to the 35, that late in the season the percentage of touchbacks naturally declines, due to weather and normal issues like heavy legged bored kickers. The kicking swing isn't any more automatic than the golf swing. Some drives are pulled low and into the rough.
I agree that Sturgis' issues started with the lousy kickoff against the Ravens. He hasn't been as relaxed or as smooth since that point. Carpenter had excellent mechanics that seldom varied.
Sturgis' misses have been narrow and from long range. It's not a problem until a midrange kick quickly sails well wide. At that point you've got a confidence and/or mechanical issue.