Research for my next book, about the OaklandA’s dynasty of the 1970s, to be published by Houghton Mifflin in 2015, has turned up boundless examples of unwritten rules from that bygone era. The latest is from July 4, 1972, in which a future Hall of Famer discusses some possible gamesmanship in Chicago. From the Oakland Tribune:
After his two-hitter against California, Catfish Hunter made some allegations against the White Sox. In his previous start, in Chicago, Hunter was beaten, 4-0, by White Sox knuckleballer Wilbur wood.
“The baseballs are bigger in Chicago when you pitch against Wood,” Catfish charged. “You can tell that when you get the ball in your hand. When you pitch 200 to 220 innings a year, you can tell by just holding one. The seams are a lot higher. I talked to [Angels left-hander] Clyde Wright before the game, and and he said he noticed the same thing pitching against Wood in Chicago. He said he threw six baseballs back and couldn’t find one the right size. All they’ve got to do is wet them and then dry them out. That makes them bigger.”
Larger seams on the baseball would add flutter to Wood’s knuckler.
Wood won 24 games for the White Sox that year, pitching a modern-era record 376.2 innings and finishing second in the Cy Young Award voting.
The Baseball Codes 
The comments by Catfish Hunter are fascinating: He exposed a whole new way of cheating! Would love to know if there is further corroboration of his charge.
It’s the first I’ve heard of such a thing, but you can bet I’ll bring it up the next time I run into R.A. Dickey, Charlie Hough or Phil Neikro … or Wood himself.
Thanks! I’m looking forward to your book on the A’s in the 70’s. I remember them well. An incredibly colorful and exciting team. As much as I hated Charley Finley, I think he had a huge influence on baseball, even more than Steinbrenner, in my humble opinion.
I think you’re right; Finley was an innovator of Veeck-ian proportions. The coda to the story is that his primary weakness — an inability to cede power to his players — played right into Steinbrenner’s strength, and the Boss ended up spending freely to win his initial championships behind Finley’s two best players.