"You're NotaTeamPlayer" often means "You don't do what I want you to do."
The phrase is mostly used by bosses to describe an employee who does not fit the mold they are expected to. I personally have never heard it being used seriously when the target is really a bad employee, but rather when the target does not knuckle under the boss's power.
"You are out of sync with the CryptoCracy."
"You did not join in the LetsPlayTeam game with the rest of us."