Ryan Howard: 58 home runs
Howard showed his incredible power potential as a rookie in 2005, blasting 22 home runs in 89 games, earning Rookie of the Year. The following season, Howard crushed Mike Schmidt‘s franchise mark for home runs in a season with 48, belting 58 home runs.
At one point, he was on pace to hit over 60, but tailed off towards the end, hitting just two home runs over the final 20 games. Howard had three more seasons of over 40 home runs and finished with 382 home runs, second in Phillies history.
Howard’s 58 home runs in 2005 are tied for 11th-most in a season in Major League history. Only one player in the league since then has hit more than 58 in a season, that was Giancarlo Stanton‘s 59 in 2017. Christian Yelich of the Brewers is on pace this season to tie Howard’s mark of 58.
Of the current Phillies, who has a shot, if any to reach Howard’s mark? The top candidates are Rhys Hoskins and Bryce Harper, but never have a realistic shot of ever passing Howard. Harper’s best season total to this point was 42 in 2015 with the Nationals. He averaged a home run every 12.4 at-bats.
Even if Harper can match that at-bat-to-home-run ratio, he’d need 732 at-bats to reach the mark. He’s never had as many as 700 plate appearances in a season and always draws a lot of walks, so Harper won’t approach the record.
What about Hoskins? He averaged a home run every 9.4 at-bats during his rookie season but tailed off considerably after the incredibly fast start. He also did that throughout only 50 games, not an entire season.
Hoskins could reach 59 home runs at 9.4 at-bats per home run in 548 at-bats. The number of at-bats is reachable in a season (he had 558 at-bats in 2018), but the home run pace seems very unlikely for an entire season. I bet that Hoskins doesn’t come close either.
Is there any player down the line that could do so? It’s always possible, but chances are substantially in Howard’s favor that his record stands.