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What does 6 red star means?

I see in our league, Teams with 6 red star staffs, is it common?
https://s23.postimg.org/pqkdpg2nf/bbb.jpg

That means you are using illegal staff and your team is gonna be deleted soon ..
Joke apart staff is capped at 5 stars and you have a better CD than your team so keep him.

it is at least 1 level above the level cap and i guess he was hired when there was this bug/exploit, where the hire button wasn't deactivated, when you opened the page of a driver/staff member directly

Dew.
If you are looking at staff employed by other managers in your league who are a higher level than you their staff may appear to you to have 6 red stars. My understanding is that the star rating is relative to the difference between the level of the staff member and the level of the manager who is viewing them.
For example... You are a L14 Manager, if you view the drivers of Aleman Gik (who is L16) you will most likely see Nikolay Zuibimov (L17) as having 6 red stars, but if Aleman views the same driver he will only appear to have 5 stars.

That explains it perfectly, thank you