Yeah. It's definitely one you can't really gauge in terms of where a "cutoff point" would be for level of play.It's not something I've even thought about since I don't know the distinction. I wouldn't be able to say whether my level of play in P4A is "low", "mid" or whatever.
Mid-level to me is basically those that know the mechanics. They just don't know how to put the pieces well together.
So to me, someone could know all their combos, but I'd still consider it mid-level if they don't know how to effectively manage meter or screen control (as an example).
I know others don't feel that way on mid-level play though, haha.
Even with mechanics like OMB and such, I still don't think there's a barrier as bad as some other games for low to mid play.
Something like BB's teching system would be one, imo. Or maybe 64 and Melee's L canceling.