Maybe you need to watch closer?
What I saw, talking AussieMen's final, was DJ changing his forehand to a loopier, higher, slower ball, then slicing harder after the first two sets.
Saw him serving out wide more often, moving to net and moving Andy to net, taking advantage of Andy's more suspect movement.
When he get's frustrated, he often started to hit much harder, then backed off after maybe 3 hard shots, because he knew he was about to miss.
And when Andy seemed to recover a bit from his toe and left hip, and started hitting better and better, DJ kept the wide serves, missed too many hard ones, but started serving wide second serves and covering his wide forehand side, forcing Andy to hit either wider or up the line.
You don't think dropshotting a obviously semi injured player is not strategy?