What would a more “plausible” Roy Hobbs resemble? A part of me wants to say Bob Thurman or Chuck Hostetler. Those were two players who entered the big leagues past the point where most players retire as position players. Of course, neither matches Hobbs’ “shot and returned with thunderous flash much later” story. Thurman was kept out of the major leagues by segregation while Hostetler only got a spot due to the World War II roster crunch.
Hostetler hit for more average, with no home runs (although that could be due in part to the materially deader ball of the wartime period). Thurman hit for more power with a lower average. Hostetler had slightly more stolen bases. Both were pinch hitters/backup corner outfielders. Hostetler had a degree of infamy for failing on the bases in Game 6 of the 1945 World Series and costing the Tigers the win-yet with ultimately few hard feelings or remembrances as they won Game 7 anyway (this would have been the fate of Bill Buckner had the Red Sox won in 1986).
Could you make a book about a fictional version of someone like one of those two, a old low-list role player either hit (Thurman) or helped (Hostetler) by circumstance? Of course. And, in my opinion, such an unusual but not overly powerful standout would arguably be more interesting than a super-player who dominates the league until his character lets him down.