No one agrees on what “Hall of Fame numbers” are. No objective criteria exist.
Here’s a game that statistically oriented fans are wont to play: Draw up the list of who would be in the Hall if it were up to you. Then devise statistical standards that accommodate your Hall of Famers but almost no one else. Declare those standards intuitively obvious. Write up your formulas into an article without explaining that you reverse-engineered from the results you wanted the formulas to produce. Then send the article to the editors of Baseball Prospectus, but don’t expect them to run it.
If you’re tempted to play that game, at least go to the trouble of expressing your numbers as ratios to the league average. Curt Schilling’s lowest single-season WHIP was 0.968, in 2002. Impressive, yes, but Bob Gibson did a lot better in 1968, with 0.853 — except he didn’t, because the league average that year was 1.120, compared with 1.369 in 2002. Schilling in 2002 posted a WHIP that was only 70.7 percent of the league average. Gibson in 1968, 76.2.
The business of comparing player stats from different eras is fraught with difficulty. Most of the Hall’s 300 members — 163, to be exact — were nominated by the Veterans Committee. Many of the names mean nothing except to baseball historians, and the records of those you do recognize are liable to be inscrutable. Sure, you might have heard of Old Hoss Radbourn, but how do you interpret his record of 59 wins and 12 losses for the Providence Grays in 1884? He started 73 games and completed — 73. For someone whose frame of reference is MLB in 2013, those numbers are too remarkable to be meaningful. They don’t compute.
When trying to quantify a player’s Hall-worthiness, we should translate all his numbers into ratios to the league average and then compare his ratios to the ratios achieved by players who have already been inducted. In the end, though, we have to accept that any player’s standing in baseball history isn’t entirely quantifiable.