Week-by-week, team-to-team football math doesn't really work. By that same logic you could say our defense allowed far less yds and points so we have a better defense. It's different game plans, match ups, and overall circumstances having made adjustments from week 1.
Week 1 games are typically pretty cagey, penalty filled, and sloppy. Plus our full offensive unit (Flacco, SSS, Perriman, Pitta) didn't play a single snap together in the preseason, not to mention it was Joe's first real game since the ACL.
We have so many weapons it's hard to imagine the offense not having a big year. Browns/Jags games are a perfect opportunity to let loose on offense and really figure out our identity on that side of the ball.