I'm going to disagree with you on the offensive comparison. The Texans are averaging 359.8 yards of offense, while the Jags average 326.1 yards. We are averaging 33 yards more a game than the Jags. In terms of total offense, not player vs player, I think the Texans have the advantage.
As for Carr vs Leftwich: Carr has a higher passer rating than Leftwich, and averages 36 more passing yards than Leftwich. So there is ammo to argue that Carr is having a better year than Leftwich. They are both having good years though.
A good argument is always spoiled by someone who knows what they're talking about