I think it is other way round. Some people are able to maintain quality over a career and that proves they are the 'auteurs' of those things.

And some other people cant reproduce the former success, which makes it much more likely the reasons for success were well beyond their control.

An auteur is just the "author", the primary creative force behind a project. Sustained success is orthogonal to that and depends on the person. Francis Ford Coppola didn't make anything of note after the 1970s, but he was still the auteur behind The Godfather and Apocalypse Now.