In 2001, Barry Bonds broke the all-time single-season home run record, taking Chan Ho Park deep for his 71st home run, topping Mark McGwire's three-year old record of 70. He'd then go on to hit another 24, setting the mark at 95. During his entire 22-year career, he hit exactly 1,000 home runs. It's not even the all-time record, because Hank Aaron hit 1,012.
Wait, that can't be right. Let's roll that back.
Bonds actually only hit 59 homers in 2001, a career high. It was one of only two times he ever topped 38 homers in a season — he never reached 60, much less 70 — and his 634 total career homers, while obviously a huge number, fell well short of record-breaking.
Hmm, that can't be right either. What's going on here?
What you're witnessing here, to an absurd extreme, are the effects of park … effects, plus the wild swings in offense over the years.
• That first section, the power-happy one, supposes that Bonds played every home game his entire career in the all-time pinball environment of Coors Field, 1999, which saw 6.3 runs/game.
• The other one, with nearly 400 fewer home runs, comes with the idea that he'd played his entire career in the year and park that were the stingiest for offense in the modern era: Dodger Stadium, 1968, which saw 3.1 runs/game.
We'll explain how in a second, but let's try this another way. The best hitting season on record — according to OPS+, which is park-adjusted — is Bonds's ridiculous 2002 season, where he put up this no-really-we're-not-making-this-up line:
.370/.582/.799, with 46 home runs and an OPS of 1.381
That one actually happened! It's an objectively silly line. You'd say "that's a video game line," except you couldn't even do that in a video game. That .582 OBP is saying that he got on base nearly 60% of the time he stepped to the plate, which is the sort of thing that happens when you walk 198 times.
So let's take that crazy line, and make it even nuttier. Imagine it was actually:
.441/.651/.949, with 61 home runs and an OPS of 1.600
You can't even comprehend that line. It's definitely a group of numbers, and it bears some familiarity to the regular triple-slash line you're familiar with, but that's unlike anything baseball has ever seen, at any level, at any time. It obviously didn't happen. But in the world of 1999 Coors Field, that's what the translation of it would have been.
So when you take his real 2001, the 73-homer record season …
.328/.515/.863, with 73 home runs and an OPS of 1.379
… and move it to 1999 Coors Field, you get …
.386/.579/1.020, with 95 home runs and an OPS of 1.599 — with, as a treat, 199 RBI
That's because when Bonds played at what was then called Pacific Bell Park, the Giants' home stadium was — as it still is — notorious for being pitcher-friendly and difficult to hit in. According to Baseball-Reference, San Francisco's park factor in 2002 was 93, on a scale where 100 is "average" and over 100 is better for hitting. (Coors Field that year: 117. Coors Field in 1999: 125.) So as hilarious as Bonds's real-world line was, it was likely hurt by his home park. He did that while at a disadvantage!
(That's shown in his splits from 2002– at home, he had a still-elite 1.314 OPS with 19 homers, but on the road, he had a 1.438 OPS with 27 homers.)
Imagine, then, what would happen if 2002 Bonds wasn't playing in pitcher-friendly 2002 Pacific Bell Park, or even in a neutral or hitter-friendly park from that season. Imagine, instead, that he was instead playing in the all-time best possible offensive environment, that 1999 Coors Field. That was the pre-humidor version of Coors, the year where Larry Walker hit .379/.458/.710, four Rockies hit at least 33 home runs … and the pitching staff posted a combined 6.03 ERA, the second-highest in the post-war era.
That's how we got these ridiculous Bonds numbers: By using Baseball-Reference's neutralized batting stats, what would some of baseball's best-ever seasons have looked like in the most extreme possible environments? What would their careers have looked like? You can read about how the translations work here; the math is quite complicated, but the short version is that it attempts to adjust both for the player's ballpark and the league's hitting environment.
So, we thought, in this time without baseball, let's go nuts. Let's find some of history's all-time best hitters and put them in the mile-high altitude of 1999. Let's do it for all their seasons. Let's do it for their entire careers.
This is, obviously, all hypothetical. It's for fun, in a time where we all need fun. It doesn't account for the "Coors hangover" effect we know to be real, the issue that gives Rockies hitters fits when adjusting back to sea level. Even Rockies hitters of the time didn't get to play in the 1999 version for many years in a row. We understand all of that, and this all also ups each player's time to a full 162, important in a shortened strike year like 1994. But still: This is a version of baseball that existed for a year (more, really, because it's not like 1998 Coors or 2000 Coors were that far off; unrelated, 1930 Philadelphia wasn't that far off either).
We'll get to Babe Ruth and some of history's other great mashers another time. For now: The Barry Bonds 1999 Coors Experience.
Bonds' new career line
Bonds, for what it's worth, hit .336/.468/.693 in 81 real-world games in Coors Field, an inflated line that pales only in comparison to the .513/.583/.949 line he put up in 10 games at Denver's Mile High Stadium, the predecessor to Coors.
Bonds, across his 22 seasons in three home ballparks (Three Rivers Stadium in Pittsburgh, and Candlestick Park and Pacific Bell Park in San Francisco), hit .298/.444/.607, for a total OPS of 1.051. Unadjusted for era or ballpark, that 1.051 OPS is the fourth-best ever, behind Ruth, Ted Williams, and Lou Gehrig.
Our purple-clad Bonds, meanwhile, hit .354/.507/.719, for a total OPS of 1.226.
Wait, "purple-clad Bonds." You need to see that. We all do. Well, maybe not you, Giants fans. Look away.
The new five best Bonds home run seasons
2001 — 95 (actual: 73)
1994 — 67 (actual: 37 in 112 games)
2002 — 61 (actual: 46)
2000 — 60 (actual: 49)
1993 — 59 (actual: 46)
The new Bonds made it to 60 four times, and note also that two of these years (1993 and '94) came at Candlestick in his first two years with the Giants. The Stick, in '93, had a hitting park factor of 93, making it just about as hitter-unfriendly as Pacific Bell was.
The new five best Bonds offensive seasons by OPS
2002 — 1.600 (actual: 1.381)
2001 — 1.599 (actual: 1.379)
2004 — 1.594 (actual: 1.422)
2003 — 1.450 (actual: 1.278)
1993 — 1.319 (actual: 1.136)
These seasons were already all absurd. Put them in '99 Coors, and they're off the charts.
The new "worst" Bonds season
In reality, Bonds never had an actively poor season, setting aside the injury-plagued 2005 that saw him get into just 14 games. But if you were to sort the other 21 seasons from best OPS to worst OPS, his weakest would have been his rookie season of 1986, where he hit a roughly league-average .223/.330/.416, a .746 OPS that had a 103 OPS+. (Yes, it seems surprising that line was league-average. The mid-80s weren't a high point for offense.)
Take that out of 1986 Three Rivers and put into 1999 Coors Field, that turns into: .267/.385/.500, an .885 OPS. That's approximately what Ronald Acuña Jr. actually had in 2019. Acuña is a star. This would have been our hypothetical Bonds's low point.
The road to 95 homers
OK, seriously though, 95 home runs. Last year set the all-time record for homers in a Major League season, and even in that homer-happy year, the Marlins as a team went deep only 146 times.
The toy we're using doesn't really allow us to get granular and say this ball would have been out or that one would have, and 2001 was well before the advent of Statcast metrics like exit velocity or launch angle. But we do, at least, have a look at his 2001 batted ball spray chart.
This doesn't tell the entire story, because part of the adjustment includes fewer strikeouts, too. The real Bonds whiffed 14% of the time; our hypothetical Bonds whiffed only 12% of the time. So imagine there are a few more dots on this chart. Imagine that the ones that are already there have an extra few feet on them, even though Coors is a larger park in some areas. It's not that hard to see how more hits + more distance = more homers.
Of course, none of this solves for the real problem. Bonds already holds the all-time records for intentional walks (688, more than double the 311 of Albert Pujols in second) and walks (2,558, by 368 over Rickey Henderson). The real Bonds was already actually given an intentional walk with the bases loaded. Imagine, now, that we're giving one of history's most feared sluggers one of history's most feared hitting environments? It's hard to hit home runs when you're getting intentionally walked 500 times.