I like that the randomly generated white haired thrall was removed for the Wheel of Pain animation, however, here are some suggestions to improve the overall immersion:
Have the Wheel of Pain stop moving when there are no thralls actively in the inventory working the apparatus.
Unlike the previous incarnations before the updates were the Wheel of Pain was pushed by white haired thrall NPCs, have the actual NPC thrall captured be animated as the one to push the Wheel. For example, if Braggi the Bold was the NPC captured, he would appear to be pushing the Wheel until removed.
If there is only one thrall actively being broken on a larger inventory Wheel of Pain (Wheel / Greater), then only one thrall (the actual one captured) would be pushing. If another is captured, then there would be two, etc.