You're missing the point.
I'm not saying a long drive leading to a TD is his ceiling. What I'm saying is that making solid short and intermediate throws (with the occasional bomb) down the field with the strong threat to run is his ceiling.
When I see EJ, I see him making 25-30 yard throws on the money, picking up big chunks of yardage, while being elusive in the pocket. In other words doing everything Tyrod can do, with less running ability, but at a higher level in the pocket.
One guy is solid, the other guy can be a top 10 QB in this league.