Who are A's and Giants' greatest home run hitters after adjusting for era?
Numbers Game created a formula to weight individual home run seasons. Over the past 100 years (since the Deadball Era), teams average 0.7925 home runs per game. We weighted each season to that number and adjusted individual performance accordingly. For instance, if teams averaged twice that number (1.585 HR/G), a player would get credit for half as many home runs. If teams averaged half that number (0.396 HR/G), a player would get credit for twice his home run total. The names may seem obvious, but home run totals have fluctuated dramatically over the past 100 years, depending on ballparks, equipment and player skill sets and strength (some natural, some not). This makes it difficult to compare stats from different eras. The Sporting Green took the top 10 individual home run seasons for the As and Giants and weighted them to the 100-year average (0.7925 home runs per game). Among Giants, Johnny Mize benefited most. MLB teams averaged 0.58 home runs in 1947, when Mize hit 51 homers, making his adjusted total 69.7 home runs. Barry Bonds record-setting 2001 season of 73 home runs, in the middle of MLBs steroid era, took a big hit. MLB teams averaged 1.12 home runs that season, so Bonds weighted total is 51.6. The last season to average fewer than 0.7925 HR/G was 1989 (0.73), the year that Kevin Mitchell hit 47 homers for San Francisco. That is weighted to 51.2, greater than any of Bonds weighted seasons. On the As side, Jimmie Foxxs franchise-record 58 home runs in 1932 (0.48 HR/G) gets bumped to a staggering 95.7 weighted. His 48-homer 1933 season shoots to 90.7. Taking the biggest hit for the As are Khris Davis and Mark McGwire. Big Macs 52-homer season in 1996, also in MLBs steroid era, is weighted to 37.8. Davis 48 homers in 2018, the height of the juiced-ball era, is weighted to 33.1. Reggie Jacksons 1969 season (47 homers, adjusted to 46.5) and Jose Cansecos 1991 (44 to 43.6) hold up well. Willie Mays has four of the Giants top 10 home run seasons, but all took a dip ranging from 2.4 in 1965 (career high-52 becomes 49.6) to 7.3 in 1962 (49 to 41.7). The most juiced season in the past 100 years (following MLBs deadball era) is 2019 (1.39 HR/G), while 1943 bottoms out at 0.34, the same amount as triples that season. Rudy York of the Tigers led MLB with 34 home runs in 1943, which is adjusted to 79.25. Nick Lozito is a San Francisco Chronicle staff writer. Email: nlozito@sfchronicle.com