Scaling and tiering can be useful, but I feel it's rather insignificant to the circumstances of both the fight and the combative capabilities (broken down extensively and observed) of either combatant.
And it's also noteworthy to figure how well each contented.
It's all well and good saying two people of vastly different powers contended with the same person.
It's a different thing to say that one contended in a stalemate and the other contended/managed to hold out for a time.
(It's also of worthy note to consider that many people do not view Canon and Legends Grievous in the same light, and would render the comparison between both showings (Mace/Ahsoka) an obsolete one, but that's a whole other topic).
It's fine to tier characters and scale them against one another, but I don't think we can complain that one seems to be competing above their bracket without looking at the context in great detail to figure out why they were able to accomplish such a feat.
Emperor339's comments