That's a question asked frequently of a number of players who were, at least in some eyes, seen as "potential Hall of Famers" during their playing days.
Consider -- teammates Doc Gooden and Darryl Strawberry were both mortal locks for Cooperstown once upon a time, but had ... issues. Albert Belle and Carlos Baerga, another pair of teammates, once played at Hall-worthy levels, at least for a time; they had issues, too, though not of the same sort as the vagabond Mets of yore.
Dave Kingman was never really a Hall-worthy player, though he hit home runs like one for a while. Don Mattingly -- nothing wrong with Donnie Baseball, he just plain hasn't been deemed worthy by voters thus far.
So there appear to be five "true outcomes" for those who fell by the HOF wayside ...
So here's your Question of the Day ...
Who fits these categories, as guys who you personaly once legitimately thought "He could be a Hall of Famer" but then ... he just ... wasn't. (And don't hesitate to "project" and include active players who seem likely to meet this same fate!)
More than just Blue Jays, oh ye true Blue fans who once saw Lloyd Moseby through a child-fan's eyes as a Hall of Famer for sure ...