Why on earth do sluggers level up when a team does?

MISSRED

Sluggers are not part of my team in anyway. Upgrades do not work for them, pennants have zero effect as well. Yet TSB decided because my teams platinum, my sluggers must be too? No, no, no, no. 
Slugger levels should only be determined by their strength. TSB gets all the brackets and matchings right but this one. I see countless gold level 5 guys with 20k rated sluggers. 
This is a huge reason guys wont evolve past silver. If you fix this, youll fix the game. 
Again, my team has NOTHING to do with my sluggers. But my sluggers are punished for me having a good team? Unfair and makes no sense.