What we should truly keep in mind is how Andy has fared at Slams and Olympics this year so far. That's where Andy's main goal is as he has yet to win a Slam and that's where he is going to give his all. This is just another Masters, which he has won quite a few times already.
I dont think he is tanking per se.
he's just not feeling it and is refusing to dig very deeply.
it might be on purpose but it could be he is having a off day.