Big part of that is fixing power related bugs in rdna1...for a 7nm card, the 5700xt eats A LOT of power, a tad more than even 12nm gpus from nvidia, which is very very bad. So the 50% improvement is just fixing a big problem and advertising it as a big improvement. Just like they advertised 50% higher IPC for Zen vs Buldozer. The biggest leap ever in IPC. Sure, when you go from a piece of crap to something half decent, the improvement is huge, but it doesn't mean you did some engineering marvel to make it happen. You just fixed your own crap.