Man, I suck this season in ranked

I've only been playing since the summer, and play pretty casually, but I've always been able to get to Platinum at least in Standard ranked.

Since it reset recently, I haven't been able to get out of Gold 4. I've looked decks up, made a Radkos and Mardu deck from ones I found online, and I keep getting absolutely crushed every other game.

Any tips or deck styles I should be looking at?