Biggest example of plot armor in this manga, Aoba and his shenanigans during the second tournament arc are not even close.
The coach guy is supposed to be very rusty after 3 years of inactivity and without proper cycles of training camps with good sparring parthers (he literally trains with amateur high schoolers lol). And yet he TKOed a much bigger and younger top-3 Dagestani fighter from Khabib's team (one of the best in world). It's either the coach is Jon Jones-level talent or it's plot armor at its finest.
All recently signed stars from Japanese MMA promotions did not do that well in the UFC, so the author needed a win at least in manga, I guess. A more realistic scenario to this fight would be something similar to Machachev - Hooker.