Same thing happened to AC for a while there. Probably down to an aging squad and just the stature of the league now. The world's best mostly go to Spain, England or to massively rich clubs who will pay them a fortune.
fwiw, they are in a very similar league position to last season, which suggests they're of similar quality.
Bale has improved immensely though and they have a real star there now. If they had a top class centre forward they'd be up there.
Man Spurs have improved so much under AVB it's unreal. They could be challenging for the title in a couple of years if they hold on to their key players and make the right transfers.