Now, 23 years later, one of two original copies of that agreement - "In the Matter of Peter Edward Rose, Manager, Cincinnati Reds Baseball Club" - is for sale. Beginning Monday at 9 p.m. and continuing through Nov. 10 at 10 p.m., Goldin Auction of West Berlin, N.J., will be offering the item in an online catalogue auction. The site is www.goldinauctions.com.
"Anything that changes the sport, anything people are talking about 20, 30 years later, that people will be talking about 50 years later, is of monumental importance to sport collectors," said Ken Goldin, head of the new auction company.
"I don't know if anyone knew of its existence or thought it would ever be available for sale," he said. "But now it is."
Goldin, 47, whose business dealings with Rose date back to 1988, believes a conservative estimate of its worth is "$500,000-plus."
The selling price, he said, might even challenge the record for a baseball document, the $996,000 paid in 2005 for the 1919 agreement of sale that sent Babe Ruth from Boston to New York.
"Knowing he could not manage again, could not get into the Hall of Fame, it's mind-boggling, absolutely mind-boggling," said Goldin of the Rose agreement. "I'm sure he signed thinking that [the ban might soon be lifted]."
Some others in the sports-collectible business see it differently.
"Pete Rose is an anomaly," said David Hunt of Exton's Hunt Auctions. "For years people speculated on his merchandise because they believed he would eventually get into the Hall of Fame and its value would then increase. Now there are many, many people who feel that will never happen. And that has hurt its value.
"Game-used bats and jerseys, things from his on-the-field career still do well," Hunt noted. "But this, while its historical significance is clear, is something with a negative connotation. It just depends on how it's viewed by the buyer."
Rose's formal attempts for re-instatement in 1992 and 1997 were denied. In 2004, his autobiography included a belated admission that he not only had bet on baseball but had done so in games involving the team he managed, though he claimed he never bet on the Reds to lose.
When Goldin started his auction business earlier this year, he contacted Rose and told him he thought the 1989 agreement would be a blockbuster for the firm's initial offering of collectibles.
"I had in my head a lot of key items that I wanted," Goldin said. "This document I thought was going to be as big as it gets, certainly for a first auction."
Rose didn't have it but put him in touch with the anonymous consignor, a collector who got it directly from the banished star. Goldin would not say whether Rose sold it or gave it away but did add that the onetime Phillie would not benefit financially from this sale.
Earlier, Fay Vincent, the ex-commissioner who, as Giamatti's assistant, also signed the document seemed to suggest otherwise.
"There is a certain sense of the absurd in turning an agreement about the abuse of our great game into cash for the miscreant," Vincent told ESPN during a televised interview last month.
Neither Vincent nor Rose, who has made a post-baseball career out of selling memorabilia and autographs, could be reached for comment.
Goldin has been a baseball collector since he was 12. He started doing business with Rose in 1988, booking the athlete at card shows and on TV-shopping networks.
The agreement's authenticity has been verified by Rose, whose letter to that effect will be included in the sale, and certified by PSA/DNA, a publicly held sports-collectible authenticator headquartered in California.
The only other original copy of the document, according to Goldin, is kept in baseball's files.
Morbid as it sounds, the fact that Giamatti, commissioner for less than a year, died of a heart attack at 51 just eight days after the agreement was concluded likely has increased the item's value.
"Significantly," said Goldin. "It's always been my personal opinion, knowing the situation as closely as I do, that had not Bart Giamatti passed away, Pete Rose would be in the Hall of Fame today. This certainly is one of few documents Giamatti signed in baseball and one of the last things of any kind that he signed."
Among the hundreds of other items in the auction are a pair of boxing gloves used by unbeaten heavyweight champion Rocky Marciano and a number of articles from the collections of Flyers legends Bernie Parent and Dave Schultz.
The minimum bid for the Rose document will be either $100,000 or $200,000, Goldin said. But even if it brings a record price, it almost certainly won't approach the potential value of the Holy Grail of baseball documents - the hand-written, signed confession of the Chicago Black Sox' Shoeless Joe Jackson.
"People constantly talk about that," said Goldin. "It was lost during his  trial and never been seen again. I can tell you that's probably a $5 million document."
Contact Frank Fitzpatrick at 215-854-5068, email@example.com, or @philafitz on Twitter. Read his blog, Giving 'Em Fitz, at www.philly.com/fitz.