I have run the team Zelgadis talks about in arena for 4 months too and i think more or less the same things he thinks.

The chance that mei standard could apply acupuncture and start a combo is so low in arena that you are really lead to think she doesn't own at all that potential feature, you basically consider the event of its application as a gift by luck, like picking up a one of a kind in a 1000 cards deck.

About Water Style - Water Whip, what's sure is that the version the clone uses have indeed a boosted chance to start a combo and apply acupuncture, very likely the chance for it to land is 90%, but about the version the Azure Fang herself ca(n us)e i'm of the same idea of Zelgadis. It's in no way higher than any other standard attack common ninjas own nor is higher than the chance to start a combo Taijutsu Attack has (1st standard). The reason why in 2.0 Monster Strenght was added to the set of Azure Fang was to give her an high chance to apply a reliable combo triggering standard attack because she missed one that worked that way without the clone.

If Water Style - Water Whip had really an enhanced chance to land acupuncture on the target and start a combo then Monster Strenght would be totally useless, since Taijutsu Attack lands more damage than Monster Strenght up to at least 4-5 stacks of reserve seal (so if you wanted damage you would select this one) and since Water Whip would have the same high chance to start a combo, but with an effect, knockdown, that could not only link directly to AF 3rd chase without the help of any specific Summon or support ninja, but also deliver acupuncture before chaos (so if you wanted to start a combo with high chance you would select the same this standard and not monster strenght). So what would be the point of Monster Strenght if Water Whip had an enhanced chance to start a combo?