Is 1953 Bowman the most error-filled card set in history?

1953 Bowman is the perfect set on its front: beautiful and pure.

But error lurks within its backs. 

Can you see the monstrous mistake? 

 If you look online for "1953 Bowman errors," you won't find much. PSA's article on 1953 Bowman Color mentions a few fumbled birthdates, a picture of one player used for someone else's card, and one mediocre pitcher (Al Corwin) with two cards. That's it. 

Al Corwin, #126

Al Corwin, #149

If you look further on the web, you won't find any errors in the set more substantial than a few misspelled names. 

As far as I can tell, no one has ever pointed out that almost every single card in both the Color and Black and White sets has some kind of statistical error. For example, Allie Reynolds' career ERA was 3.30, not 2.76, going into 1953. 

Most of the cards have miscalculated career batting averages or ERAs, just like Reynolds. Many of the errors are small - a 5.04 ERA instead of 5.02 - but some, like Reynolds, are kind of obscene. And if the batting average isn't wrong, some fielding stat probably is, and some cards even have seasons missing from the career totals. (The most flagrant of these even mention the missing season in the write-up. Al Corwin is a good example. His bio mentions his 5-1 1951 season, but his career stats only show his 1952 season. The backs of his two cards are identical except for the card numbers, so this holds true for #149 too.)

When you put all these different types of errors together, only 29 of the 224 cards Bowman released in 1953 do not have a statistical error. If there's any set with a higher percentage of error cards, I'm unaware of it.

Some back-story: 

I noticed a few cards with truly flagrant errors long before I realized that they were part of a theme. I noticed the mistake in Allie Reynolds' career ERA not too long after I got the card for Christmas, 2019. (An Ode to 1953 Bowman: Christmas Edition) 

If I remember correctly, the card that made me realize that the error was not an isolated event, that 1953 Bowman was rife with the iniquity of incorrectness, was a card I got in a lot this spring: Matt Batts, B&W #22. 

My mathematical mind writhed when I saw a man with 268 hits in 979 at-bats listed as having a batting average of .260. 

When I began noticing all these blatant errors, I wondered whether there might be subtle errors in other cards. I started checking and behold: errors were here, there, everywhere. I began checking every card sometime this summer, and worked on the project off and on until I finally finished yesterday. 

Disclaimer, required by law: The same love of statistics that led me to notice these errors in the first place, and then check every single card for more, also prompts me to provide various statistical breakdowns about aforesaid errors. You have been forewarned.

A preliminary note on my method: My goal was to see how many cards had errors, not to exhaustively determine every single error. For that reason, I only checked a player's fielding stats if his batting stats were squeaky-clean, which means that there may be significantly more fielding stat errors than I found. 

Acknowledgments: I used TCDB's pictures both for my statistical sleuthing and for this post, and Baseball Reference for the players' career totals up to 1952. I used Since I Left You by The Avalanches for musical distraction as I checked and rechecked; stats become banal even to the most hardened stat junkie after a while. 

In Bowman Color, out of 160 cards, 13 are errorless. Of these, three of the cards have no stats listed (44, 69, 93), five are of rookies with just one year of stats (83, 97, 98, 112,153), and one is a coach (95, Wally Moses). Only four cards of players with more than one season in the majors are errorless: 16, Bob Friend; 47, Ned Garver; 53, Del Rice; and 78, Carl Furillo.  

Out of 94 batters, 73 have incorrect batting averages, nine (at least) have incorrect fielding stats, two have incorrect batting counting stats, and five have one or more seasons not included in their career stats. (George Shuba was missing three.)

Out of 53 pitchers, 48 have incorrect ERAs and five have a season not included in their career stats. (Two of the five are Al Corwin.)

Out of eleven coaches and managers, six have incorrect fielding stats, two have incorrect batting counting stats, one is errorless (95, Wally Moses), one has no stats (Charlie Grimm), and one has both incorrect fielding and incorrect batting counting stats: 57, Lou Boudreau. Notice that they all have correct batting averages. 

For Black and White:

Out of 64 cards, 16 are errorless. Of these, eight are rookies with only one year beneath their belts: five pitchers and three batters. The other eight are all pitchers. 

Out of 33 batters, 29 have incorrect batting averages, and one (36, Jim Piersall) has a season missing from his career stats. Only three are errorless, and they're all rookies. 

Out of 29 pitchers, only 14 have incorrect ERAs. Another one has a counting stat error and another one has a season missing from his career stats. Of the thirteen errorless cards, eight are veterans - a relatively impressive number. 

You can actually pinpoint the place where Bowman suddenly started getting their ERAs right. Every pitcher who'd pitched in more than two seasons received incorrect ERAs up to card #40, which gives Larry Jansen's correct career ERA. After that point, Bowman got 7 ERAs correct out of 11 non-rookie pitchers, including five in a row from #40 through #52. 

There were only two managers - Casey Stengel and Bucky Harris. They both have incorrect RBI totals, and Bucky is shorted a game from his career total. 

A clear pattern emerges from the batting averages: In both Color and B&W, a clear majority of the batting averages are too low. In Color,  26 of the listed batting averages are too high while 47 are too low. In B&W, 8 are too high while 21 are too low.

There isn't strong evidence of a pattern in the mistaken ERAs. In Bowman Color, 22 of the listed ERAs are too high while 24 are too low. In Bowman Black and White, four are too high while ten are too low. 

For your possible delectation, I will list the most egregious errors:

#22 Color - Bob Porterfield's ERA should be 3.56, not 4.66
#53 B&W - Morrie Martin's ERA should be 4.64, not 5.67
#114 Color - Bob Feller's ERA should be 3.21, not 3.93
#68 Color - Allie Reynolds' ERA should be 3.30, not 2.76
#88 Color - Joe Dobson's ERA should be 3.62, not 3.13
#29 B&W - Sid Hudson's ERA should be 4.33, not 3.89
#66 Color - Mel Parnell's ERA should be 3.38, not 3.79

#58 B&W, Jim Konstanty, lists 76 career strikeouts instead of the correct 177. 

#8 Color - Al Rosen's AVG should be .280, not .221
#134 Color - Johnny Pesky's AVG should be .310, not .270
#18 Color - Nellie Fox's AVG should be .284, not .253
#7 Color - Harry Chiti's AVG should be .293, not .321
#24 Color - Jackie Jensen's AVG should be .275, not .250
#6 Color - Joe Ginsberg's AVG should be .245, not .269
#30 B&W - Walker Cooper's AVG should be .288, not .264
#34 Color - Gil Coan's AVG should be .258, not .281
#29 Color - Bobby Avila's AVG should be .301, not .280

I'm not sure what it means for three of the worst batting average errors to take place on three consecutive cards. 

I'm bugged by the question of why exactly Bowman made so many errors - was whoever calculated the career averages and ERAs just really bad at using a slide rule? And how could a baseball fan have not seen the implausibility of some of these figures? Al Rosen had been a big major league star for three years; how could his career batting average have been listed as .221!? My summer job this year (okay, my first summer job ever) was as a proofreader. I really wish I could have been there for Bowman.

And why did they make the specific errors they did: why were averages and ERAs wrong for career stats and right for 1952 stats? Why are the career batting averages correct for managers? Why do the career ERAs become way more accurate two-ways through the B&W set? If the statistician discovered his error, why didn't he go back and change his prior mistakes? I can't think of any plausible hypothesis to account for these mysteries. 

I will leave you with a spreadsheet instead of a solution. Here's a Google Sheets file with the details on every card in both sets: https://docs.google.com/spreadsheets/d/1vU10-rGByr7aXHSZdzNrQve1-RMUumK8M5TgMDTa2_g/edit?gid=0#gid=0

Update: CardBoredom pointed out that a number of the batting averages were calculated by adding up the player's season batting averages and averaging them out. That method seems to work all the way for batting averages all through card #121 of the Color set but not afterwards.

I've only checked the method for a few pitchers' ERAs. It works for #66 and #87, but it can't explain Bob Feller (#114.)  More research is required.