IIRC most of his reforms were just making official things that people had been doing for years anyway. Wealthy generals had been buying up their own private armies unofficially, he just admitted to it and legalised it. Nevertheless, it can't be denied that he was a very good general and as such just being in the right place at the right time wasn't at all correct. The Roman system showed a remarkable ability to just throw generals at a problem until one proved competent enough to win. Someone would have eventually managed a victory, butthe major point is that Marius was good enough.