The +1 level is a troll to discourage active managers. You got a nice strong 6* squad? TE would match you with +1 level so that you will meet better teams.

U spent more tokens and make your team even stronger 7*? Next season you will get +2 level. Its a never ending loop.

One day you will realise that keeping your team at 80% or 180% offer you the same chance to win cup and CL.