Did I say cup didn’t matter? Maybe you mistook me for @Scarecrow?
Anyway, as a cup dropper I always drop my trophy to low diamond (2400) that way I can get easier opponent (below 4200 TP) so I can fill my chest easily.
For me that is the importance of cup, not higher the better, but just at the right number of cup where I can get easy opponent but I can also open my raid chest in the highest league.
What matters in raid is not cup or account level but team composition. I can easily take down a team with Kunchen tank with 4200 (I have previously did it against 4600, notice that my opponent’s level is far above me) power with a team of: Vivica - Joon - Sonya+18 - Ariel - Wu Kong+18 even though my team only have 3990 power and my cup/level is below my opponent.
The key is stacking against the tank and bring heroes that counter their skill. In my case I bring 3 yellow against Kunchen who is a purple tank. I also bring Viviva and Ariel to cleanse my team from Kunchen’s ailment.
Using stacking, you can walk over them even if their team is stronger than your team.