Maresca won conference league against clubs nobody ever heard of and got wildly outplayed by the first serious opponent he faced (in the final, lol) until individual brilliance bailed him out
In CWC also easy route to the final. Group stages got absolutely hammered by a Brazilian side. Red card saved him against Benfica, unbelievable luck against Palmeiras and fairs did well against Fluminense in semis and complacent PSG side in the final
Overall probably not even top 10 managers this season. And securing top 4 in the premier league is no achievement with squad that's worth gdp of some smaller country
If you wanna dissect his achievements that way, I could do the same for Enrique and for several other managers.
Regardless of its relative importance, every tournament presents its own challenges. While the conference league is played against "nobodies", they are usually played under hostile atmosphere, difficult turf (some of them synthetic) extra-motivated opponents vying for a title, and for a EL spot. Even if you wanna dismiss it completely, it is still a trophy and having a good team doesn't always guarantee success.
The top 4/5 was very closely contested last season, with Chelsea finishing outside CL places in the previous two. So he brought them back into the CL when there were questions surrounding them, and even being mocked at for their surplus signings. A winning formula takes time.
Saying he beat only a complacent QSG is like saying QSG beat only a deflated and demoralized Inter in the final. It doesn't matter if they had an "easier" route, they comprehensively beat the European Champions who were seen as an indomitable and invincible force by almost everyone and their grannies. That myth was broken by Maresca, tactically more flexible than any of my aforementioned managers. And since these International tournaments are given a lot of weight when it comes to individual awards. Don't be surprised if he makes a top 3 finish.
You can disagree about top 3, but to say he's not even top 10 is an irrational assertion.