But those problems aren't necessarily mutually exclusive. When your offense struggles, especially against a team like the Jags who are LOADED with speed at the wideout and TE positions, your defense has to play more snaps, and it's more likely that your DBs get overworked chasing after thinner, faster guys. And so people get open. So if the offense can get even a mediocre run game going, I think we start to see our DBs having less trouble keeping up over the course of the games.
Also, it's worth mentioning that every QB, not just Blake Bortles, has trouble with accuracy beyond 20 yards. Even Joe, who everyone always says has the best deep arm in football, frequently struggles to hit wide open receivers way downfield, because it's just that hard to do, even at the highest level of football. That doesn't mean that you should make a habit of leaving guys open, but it means that the chances of a team regularly beating you that way are small compared to other potential weaknesses, like a porous run D or not being able to keep up with TEs/slots on crossing routes.