I was talking about AP and types of strength. Mangle getting dismantled by kids is an anti-feat for Durability. The kids damage Mangle's joints specifically, but not the arms, legs, torso, etc. of the endoskeleton which are all fully intact barring a few loose wires. Even then, the animatronics' joints already have 10-C Durability for this exact reason.
It's also worth noting that, in a VsB match, if a character can render an animatronic helpless enough to systematically unscrew or tear off each joint, that character's won regardless of said joints' durability. It's not like the kids punch Mangle in the chest or anything, they just take it apart, so there's no reason for the animatronics to have 10-C durability for all of their endoskeleton.
If you're saying that just the joints are 10-C, then I agree. Anything else being Tier 10, I'd probably beg to differ.