How old are you? Do you remember the 1984-1995 Drafts?
These were the core drafts during Dan Marino's career, do you remember how bad they were?
Do you remember these first rounders?
Jackie Shipp, Lorenzo Hampton, Eric Kumeroh, John Bosa, Sammy Smith, Randal Hill, Billy Milner...one first rounder traded away for Hugh Green who had a very short career in Miami?
I'm not even gonna bother going into how bad the rest of the rounds were.
A QB can't do it alone, you obviously have to draft well at other positions as well.
There is no guarantee drafting other positions won't bust as well.
So to answer your question, with absolutely horrible drafts supporting him, Marino won the 3rd most games of any QB in history, got mediocre football teams to 3 AFC Championship games, won one AFC Championship, got a team with a bottom 10 defense and pathetic core of runningbacks to a Superbowl on his back.
So your example, is a bad one.