There is no quickness or acceleration ratings this year. In fact there is only one rating that determines speed and that is speed itself.
Speed is defined as straight line speed in this game and how quickly a guy can get up to max speed while running.
There's nothing determines a slow footed guy or quick footed guy defensively this year. Unless they tied all that into speed itself which doesn't make much sense to me if that's the case. Add in fact that people no longer have to use their feet because of all the sliding and it just makes things tougher to gage as to what defender is slow and what defender isn't now.
Triple threat seems to be the best way to accomplish what your looking for and that's because the only rating defensively is on ball defense. Find a guy with low on ball defense and he'll be more vulnerable vs the triple threat move. Foot speed should also factor in but hey it's not there anymore.