How huge is the difference between 6*/7* Thrawn.

I beat 5star with a lvl59 squad 80% said its imposible 1 try and got him. but i had some decent mods and it worked so i.m.o. mods, and gear ability lvl, etc says alot more than just the player lvl some squads with 5/6 higer lvl did not beat him cause they had weak mods.