Mighty Mouse was consistently fast, fast movement, combos and defense but I don't think he has the quickness/"acceleration" that Volk has. Volk is already super fast on his feet with good combos and counters but I feel like the thing that really makes him stand out is his ability to change speed/accelerate so quickly into a combo or in the middle of a counter, he may be throwing normal jabs and leg kicks then suddenly he throws a combo that is twice as crisp and quick as anything else he's thrown. I also think a lot of his speed comes from the fact that he's anticipating what opponents are going to do based off of his feints and offense, similar to Anderson anticipating counters and looking super human, Volk knows how your most likely to react and what you'll probably throw based on his position so he's pretty much countering or moving before you have even thrown the counter he knew was coming.