Most passes inside the 30 of the opposition these days isn't a direct end zone route...more & more relying upon YAC. The toughest defensive assignments are when they know the QB has legs for either scrambling for positive yardage or scrambling for extra finding a receiver open.
This isn't simplistic "good enough" or "not good enough" ... or they wouldn't likely be in an NFL uniform... it's about throwing wrinkles to the defense
In baseball, managers will bring in lefties to throw to lefty batters. They might bring in a speedy pinchrunner @ 3b to force the infield to play in with less than 2 outs...
Your "not good enough for midfield" comment is like critiquing a baseball manager who brings in a reliever for a starter ... even tho that reliever is "not good enough" for for the starting rotation.
Inside the 30, but eventually you’re going to be in the tight zone. You’re going to be inside the 10. You’re going to be goal line. And then you need a QB that’s more accurate.
Actually it is as simple as good enough or not. You either can throw accurately in tight space or not. Wrinkles are nice, they help keep the defense guessing. But at the end of the day the QBs job is to complete passes.
Baseball and football are VASTLY different games. 90% of baseball boils down to a one on one battle between the pitcher and the hitter. Football is almost never a one on one battle, it’s 11 guys trying to out smart and out perform 11 other guys. Baseball pitchers are easily divided into guys that have the skill set to go multiple rotations and guys that don’t. The relief pitcher concept is built around realizing that your guy with just one pitch he does well will get killed if he has to go through the rotation multiple times, but if you put him in a situation of 9 outs or less he’ll be OK. Relief pitchers are innately not as good as starter, but they can fill a roll.
There’s no role in the NFL for relief QBs, because there’s no set of down available for the guy whose not good enough to be the starter. We’ve seen that in the failure of the wild cat, which basically was doing exactly what you propose, and worked OK for about half a season. Then defenses go wise to the fact that the offense was about to hand the ball to a guy who can’t throw for crap, and now it’s dead. Remember the Jets picked up Tebow specifically to become a wild cat heavy offense, and then every time they tried to use it it failed, not only did Tebow not accomplish anything, but getting yanked out for random plays killed Sanchez’s rhythm, and they have since fired everybody involved in that idea.