It is very normal for u guys as u just hit the level requirement for blue->purple. Hence even tho u are still full blue, or semi blue with some purples, u will still be matched with lv 54s or slightly higher and their teams will be full purple. Just lvlup asap and after a few days u will be fine after u got all ur purples. And yea, this is where "hard mode" comes bcus purple unlocks several critical 4th skills which can make some heroes very strong/annoying to deal with.

and u are pretty unlucky to reach this stage ON A CRUSADE EVENT.