The AI doesn't crack your set, nor can you avoid re-ranking.
Basically, your reputation will probably rise as you have won the Champions Leage (but as you're a big club it probably won't rise too much). This means you may come up against a few more ultra-defensive teams, so you may need to use a few more "control" tactics, to borrow the wwfan terminology.
Keep your old tactics - they clearly work. But you may need a "plan B" which is a more expansive way of playing to break down the opposition.
Check wwfan's
How to Play... thread for a better explanation than I can give.