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Replace Player

The ideal system would be if every time you bid on a player while you had all slots full, you would be prompted with your roster and asked to choose who you would replace if you won the bid.
That way you can still bid on upgrades for your top laner and you only cut your top laner if you actually sign a new one.
You wouldn't be able to choose the same player to replace for more than one bid. IE: you can't bid on 5 players and say you're replacing your mid every time, you have to provide 5 options as replacements.

Currently the system is a little limiting because you miss a day of stream income and also risk having a blank spot in your roster if you don't secure the bid.