I would argue both.
Their own fanbase admits, teams that man their WR's with over the help do better than pure zone teams.
We were mostly zone and not snuggling up to their WR like the teams where Tua had a rough time. there is video evidence proof of this.
I would say its both better teams and they are figuring out that tua is throwing to places on the field and their star WR's are just running to that spot. Can't do that when there is a man on top of the WR's as well.
I would argue both.