Was wondering if anyone had a list [or even if it has ever happened…] of cases where a batter hit a home run off a pitcher who wasn’t yet born when the batter debuted in MLB.

I think the closest Barry Bonds came to this [so far] was his homer off Felix Hernandez on 16 June of this year: link. Hernandez was 52 days old when Bonds debuted on May 30, 1986.

David Clyde was born on 4/22/55

Harmon Killebrew, who made his big league debut on 6/23/54, homered off Clyde on 9/12/73

I’d start here with the list of oldest players to HR.

I know Julio Franco set the record this year, but he hit it off of Scott Linebrink, who was born in 1976.

The closest I can find for Franco is a homer he hit off Chad Cordero. But Cordero was born 36 days before Franco’s major league debut.

Found one!

Carlton Fisk [debut September 18, 1969] off Todd Van Poppel [born December 9, 1971]
http://www.retrosheet.org/boxesetc/B09110OAK1991.htm

Fisk’s last double-digit HR year; Van Poppel’s MLB debut and only appearance of ‘91.

Well, if you had to guess, you just might pick this pair.

Pick a batter who was in the bigs really early and had a long career, a bonus baby maybe—Al Kaline.  Add 20 years and think about who was a kid pitcher who was also up early—Frank Tanana.

Kaline’s first game: 6/25/53
8 days later Tanana’s born:  7/3/53
Twenty-one years later they meet:  8/28/74

I’d bet that Mel Ott took a young’un deep during the War.  With not very long odds, I bet it occured more than once.

The efficient way to do it is to write something to parse the Retrosheet Event Logs. But that would deprive me of the fun of discovering baseball names I hadn’t thought about in years.

Edit: Said parsing program is now mostly done. May have time to work on it more tomorrow or on the weekend.

Criminy… So far it looks like Fisk was the only player to do this between 1985 and 2001, based on the Retrosheet event files that are available as of today.

Here’s one of those referenced above.

Al Kaline [debut June 25, 1953] off Frank Tanana [born September 9, 1973]
http://www.retrosheet.org/boxesetc/B08280DET1974.htm

Kaline led off the bottom of the ninth inning with his home run and gave the Tigers a 2-1 victory. He would hit 3 more homers in 31 games (all starts) before retiring at the end of the ‘74 season.

Tanana went 8 innings (plus one batter) in the loss and saw his record drop to 9-16 on the year. Mickey Lolich threw a complete game and scattered 6 hits for the win.

Turning the question around, here are some homers by players not yet born when the pitcher debuted in MLB. This covers years 1973-2004.

07/13/1986 - Ruben Sierra off Phil Niekro
09/13/1986 - Jose Canseco off Phil Niekro
05/31/1987 - Mark McGwire off Tommy John
05/31/1987 - Mark McGwire off Tommy John*
07/05/1988 - Ruben Sierra off Tommy John
09/19/1990 - Ken Griffey, Jr. off Nolan Ryan
06/22/1990 - Ken Griffey, Jr. off Nolan Ryan
04/26/1991 - Carlos Baserga off Nolan Ryan
07/28/1991 - Travis Fryman off Nolan Ryan
05/26/1992 - Ivan Rodriguez off Charlie Hough
08/27/1992 - Kevin Koslofski off Nolan Ryan**
06/22/2002 - Vernon Wells off Mike Morgan

* - Not a mistake; Big Mac got him twice on the same day.
** - 5 times might just be a record for these chronological indignities.

Edit:

Looks like there’s just five more in the Retrosheet Event Files which go back [incompletely] to 1957.

08/21/1962 - Boog Powell off Early Wynn
09/28/1962 - Joe Pepitone off Early Wynn
06/21/1964 - Rusty Staub off Warren Spahn
04/30/1965 - Tony Perez off Warren Spahn
08/31/1965 - Alex Johnson off Warren Spahn

44magnum is right in his post. What is news is that Killebrew actually victimized Clyde TWICE; once in ‘73 and again in ‘74.

http://www.retrosheet.org/boxesetc/B09120MIN1973.htm

Killebrew’s homer was the only run Clyde gave up, but he was pulled after 2 1/3 innings with runners first and third, no outs and Killebrew coming to bat again.

This followed 4 prior starts where Clyde lasted only 9 innings TOTAL while yielding 20 runs (all earned) on 19 hits and 12 walks with 11 strike-outs. Guess Whitey Herzog had seen enough…

http://www.retrosheet.org/boxesetc/B05240MIN1974.htm

Again Killebrew got to Clyde in the third inning and although he didn’t chase him, Clyde lasted only one more batter (Bobby Darwin drew a walk).