The essence of the matter. Even if he does it on purpose (and my gut tells me he doesn't), the opponent still has the chance to just ignore it and keep doing his thing.
MTOs, on the other hand, physically prevent the opponent from playing. It's not just a mind game anymore.
Those things are not the same, not by a longshot.
Not really. Ask any tennis player, and they will tell you that one of the most difficult things is to play an injured opponent. Unless you are a very strong-willed individual, it is VERY difficult to simply "ignore" what's in front of you (an injured opponent). The effect is sub-conscious, more often than not. Your mind is giving you false signals, telling you that "you have him" that you do not have to play high-risk tennis anymore "just move him around the court and that will be enough."
Human beings follow the path of least resistance. It is ingrained in us all. Meaning, you will choose the path towards your ultimate goal (winning the match) by doing no more than what's necessary. When a player plays at a very high level, what is necessary is outside of your comfort zone, and you have no choice but to raise your game and play high risk tennis. When the opponent is injured (or pretends to be), path of least resistance tells you (falsely) that you can achieve your goal (win the match) by getting back to your comfort zone, which is only natural. Nobody wants to be out of their comfort zone. The mind plays tricks on you. That is why only the very best can "ignore" these mind games consistently, but even they fail from time to time. But more often than not, the very best players are strong-willed pros, impermeable to tricks and mind games.