IIRC, during Hard Knocks THill specifically said the coaches were getting on him about his drops. His footwork back there is something he needs to work on.
You're probably right. One of his sacks vs. the Panthers was because he didn't step up into the pocket quickly enough.
I've watched that play several times, and Johnson was back there awfully quick. To me, blaming that sack at all on Thill is just a means of deflecting some of Martin's fvck ups to someone else, so he doesn't seem quite so inept.
There is no deflection. There can be more than one person who doesn't make the correct play. In this case, Martin let his man by him quickly, and Tannehill didn't utilize the pocket.