High level difference in the Cup means lower star teams for that level, so there are chances that its in inactive team or, on the other hand, someone playing the quality game. Similarly, I dispatched lvl 7s easily but I'm now behind versus a 1 level up team that bought 5* (for them) after the draw.

Other than at the highest level in my experience the successful Cup teams are those that can and do develop after the draw. CL is for those that are already developed.