Guessing this is based on the fundamental execution needed to win with these characters at the very top level.

Akuma and Eliza at the very top imo. Move Geese down one. Master Raven down one, her biggest executional difficulty is crouch dash looping/cancelling and iWS which isnt used for looping in combos, just starting combos/mixups. Marduk up one, maybe even two due to VTS Cancels. Alisa up one and Claudio up two because they need to do iWR moves all the time which I'd say is at least Average although the rest isn't too difficult.

Asides from that I feel like there could be one more executional difficulty tier between High and Average with Drag, Marduk, Julia, Armor King and Steve. I feel like those characters aren't quite as executionally demanding as the others in High at the max level and some of their high execution lies purely within combos that are a step down from the others. I know it sound dumb but maybe Alisa and Claudio could be up there too. Reliable point blank iWR seems to be essential for them and that's definitely higher than the rest in Average.