Been going for it on 4th down all game long.....for 2 reasons:
1 - the data says you should (it's always been less than 4 yds to go)
2 - the inherent advantage it gives you - if you have 4 downs to gain 10 yards and your opponent only has 3, advantage you
.
It's not a ho-hum case of "oh geez, we have to go for it to stay in this game because their offense is so good." Their offense has been that good, but that's not the "why" behind it.