I said something that was off base in my most recent FanGraphs chat, which probably happens every week. In this case, however, having done the research in the area that qualifies as my wheelhouse — the Hall of Fame beat — it’s worth setting the record straight.
With Ronald Acuña’s debut fresh in mind, reader BK asked me, “What is the highest probability you would give to a rookie of making the Hall of Fame? Over [or] under 5%?”
My response was, “It depends upon the rookie. An overall No. 1 prospect who’s reaching the majors for good at 20 years old and then succeeding, I might say 5-10%. That’s just off the top of my head; guys who can stick at that age are by far the best HOF prospects.”
Leaving aside the subjectivity that comes with labeling a player an “overall No. 1 prospect,” I should have remembered based upon my reading and research that any playing time in the majors at such a young age gives a player about a 5-10% chance at Cooperstown. Using the Baseball-Reference Play Index, here are the number of position players who had at least one season with a plate appearance at each age from 18 to 21 (using the June 30 cutoff convention) and the rates at which they reached the Hall of Fame:
In calculating the percentages, I’ve excluded active players — such as Adrian Beltre, Bryce Harper, Manny Machado, Jurickson Profar, Mike Trout and Justin Upton as 19 year olds — because of course they’re not yet eligible for the Hall.
Using a 100 PA cutoff to fulfill the “significant playing time” requirement, here’s the breakdown:
In both tables, players may be counted more than once; for example, Mel Ott is one of three Hall of Famers and 11 players who qualified at age 18, and one of 13 Hall of Famers and 59 players who did so at 19, et cetera. For the 20-year-olds, the list of 33 qualifiers who are enshrined includes Ott, Ty Cobb, Tris Speaker, Jimmie Foxx, Rogers Hornsby, Ted Williams, Willie Mays, Mickey Mantle, Hank Aaron, Roberto Clemente, Al Kaline, Frank Robinson, Brooks Robinson, Johnny Bench, Robin Yount, Rickey Henderson, and one from each of the last three Hall classes: Ken Griffey Jr. (2016), Ivan Rodriguez (2017) and Jim Thome (2018). That’s a lot of inner-circle guys, if you care to make that distinction.
For the qualifiers at age 20 who are still active, I present you with the whole list:
Based on the data above, we should expect three or four to wind up in Cooperstown, but I’d suggest taking the “over” on that count. Beltre, with his 3,075 hits, status as one of the game’s greatest defensive third basemen, and the No. 4 ranking in JAWS at the position, is a lock. Cabrera, with 2,662 hits, 464 homers, and the No. 11 JAWS ranking at first base — already above the standard — is pretty close to a lock as well, as is Trout, who already ranks ninth among center fielders in JAWS and fifth in seven-year peak despite having played just six full season and change. Past MVP winners Harper and Stanton are probably the next two players, odds-wise, but they’ve got much more work to do than Trout. And note the presence of Acuña’s teammate, Ozzie Albies. Check back in 25 to 30 years and see which of these guys panned out.
Brooklyn-based Jay Jaffe is a senior writer for FanGraphs, the author of The Cooperstown Casebook (Thomas Dunne Books, 2017) and the creator of the JAWS (Jaffe WAR Score) metric for Hall of Fame analysis. He founded the Futility Infielder website (2001), was a columnist for Baseball Prospectus (2005-2012) and a contributing writer for Sports Illustrated (2012-2018). He has been a recurring guest on MLB Network and a member of the BBWAA since 2011. Follow him on Twitter @jay_jaffe... and Mastodon @jay_jaffe.
It’s noteworthy that these stats don’t make any adjustments for wearing your cap off-center. His wCAP+ score is much lower.