You looked really good at that contest.I never trained them directly ... but listen to @jackedpotato ... when ever your doing a lateral raise, seated row, t-bar row protract or pre squeeze your traps and rear delts and they will start to pop. I did a lot of heavy rowing exercises... that is where I got my rear delts. My delts at 52 competingView attachment 10367
So I can be that way in 2 years also, lol.