Mobility is such a big part of football now, in the NFL and college. Having a QB who can really hurt a defense running the ball, like Jalen Hurts or the typical Ohio State QB of the last 6-7 years, is a major part of the position. If a QB can't do that, they have to be a phenomenally good passer to make up the difference. But Drew is not a phenomenally good passer. He can make exceptional throws on occasion, but his throwing game is brought down by his lack of consistency/mechanical problems. His throwing game is also affected by his lack of mobility, because has to bail earlier than a quarterback with more quickness, and he has a harder time moving behind the LOS to buy time and get a throwing lane.
I think for a long time the analysts of the football world were just assuming that Allar's mechanics would get sorted out, that as he learned the game and got comfortable running an offense, that he'd throw the ball more consistently. But that hasn't happened yet, and he's now in his third year as a starter, so while we still hope, it's not likely to happen at this point. Probably what you get with Drew is what you get. If the team's going to be elite, it's going to take a superb defense or a superb offensive line or both.