Throwing the ball deep requires sound, sustained pass blocking, not the kind of blocking on passes that end up going deep because a RunPassOption play ends up being a long throw. But the kind of blocking required on pass plays designed to go deep.
Longo himself has acknowledged that this OL indeed has that problem. When your OL's strength is being over 300 pound road graters, and its obvious weaknesses are in playing smartly as a unit and in pass protection of deep balls, which plays take longer to develop, then you are going to feel a need to call more pass plays that are shorter routes; keep the TE blocking as much as possible, which renders him a nonentity as a receiver most of the time; pass more to RBs than you would otherwise. And your QB is going to feel the itch to press the ball deep many times.
OL issues are central to all issues on this offense.