performance enhancing drugs, or what is banned today, go back to the 19th century. Stimulants, Testosterone and other supplements were developed and available as early as the 1920s
Cy Williams lead the NL in homers with 18 in 1920 (148 games, 590 at bats). 3 years later Williams hits 41 homers in 136 games and 535 at bats.
Babe Ruth led the league in 1918 with 11 homers (95 games). 2 years later he hits 54 homers in 142 games.
im sure there are countless examples in the past 90+ years of guys who would have a spike of 15+ homers. Bonds, Sosa, and McGuire's numbers don't look that out of the norm compared to the rest of history. There has been a guy hit 50+ homers in every decade since 1920s, Until the 1998 season, there had only been a few seasons where a guy hit 60 home runs, but plenty of guys had 50+ seasons, including Ruth 4 times, on a 154 games schedule. Since 1998 there have been a couple of 70+ seasons, and more 60+ seasons, on a 162 game schedule. So really the numbers are about the same as they have been for the past 90 seasons.
thats a lot of words to say that 73 homers in 2001 doesnt seem that out of the ordinary as 60 homers in 1927