You have a good point there mate. We have seen quite many examples for that so far. For example Frank Lampard... He didn't have a consistent time period with Chelsea and was replaced in the middle of his 2nd year there. You know what happened with Tuchel after taking the job from Lampard later. 

We have an example like Xabi Alonso also on the other hand. He started his career in management way stronger with Leverkusen. So there is really nothing such as an impressive player will definitely be successful as a manager too.