This is nostalgia talking. In the OG trilogy, Thrawn was killed in a painfully obvious coup that any competent commander should have seen coming for miles. His constant dismissal of the Noghiri was idiotic. He may not have known Leia was Vader’s daughter, but something was obviously happening with their society that he just waved away like nothing.
In Ahsoka, he has next to nothing to work with, uses his meager resources efficiently, and achieves his only goal completely (aside from Ezra’s infiltration anyway). Babylon’s betrayal is the only reason the heroes achieve anything at all. At the end of the day, Thrawn has always been a fun character who primarily looks like a genius compared to the complete idiocy of other imperials.