I think depends what cards you get, or what hero you develop. I never had one hero as a favourite. Then, as galactic came out I started using a few more consistently. I then started favouring Wall knight and he has got me to UL twice, so I've invested in him. Now, my Wall knight is not getting the wins, he might win the occasional but not enough to rely on in rank. It can feel like a kick in the teeth from the game, when you've been collecting for a specific hero - then all of a sudden new set of cards and it all feels wasted. I'll also add to that the cards that were coming from packs were pretty shabby, only worth recycle - not because I've so many legendaries, or super rares.. but because nothing of any value was coming out of them. We all know recycle is low value, but better than nothing.
Unless a plant can be buffed fast, or there is hard removal your game is over. Now, from that I can either play as zombie, buy cards til I get what I need to fight back, recycle half my cards to get what I need to fight back, or just forget getting UL this season and give up.