If I'm a QB poor team, it could make sense to build a good Oline, WR corp and RB corp before getting that QB. Especially before drafting a young QB.
What I have observed is that bad teams select a QB, and then he has a poor Oline and few weapons. So, he struggles mightily as darn near any QB would on that team.
A team with a good oline and some good weapons can do well with just an average NFL vet. But a team with none of those things will do poorly with a vet or a hotshot young guy.
Improve the team, then get the QB.