The solution is to implement a "morale" system - where both players lose morale faster if they are losing competitive games (so that it costs more blues to get them all the way to "Superb") and also make them perform worse in the match algorithms. This will produce more "troll results" based on the numbers, but for example a 150% team that has lost 10 in a row should play worse and should lose to a 110% team that is undefeated (with say, 8 wins and 2 draws) of it's last 10.

Either that, or just make individual players perform worse if they are not starting regularly in the correct positions for competitive play. So if a tanker uses all his 50% backups to play league, his 150% "stars" will play like crap when they go in for association games (and, same as above, should then lose to "weaker" opponents).

"Winning begets winning" after all...