The material had been salvaged from an Oakland Coliseum Dumpster decades ago by a ballpark employee who had kept it all in his garage until selling it at a flea market recently for less than $200.
The flea-market purchaser quickly auctioned the lot on eBay early in 2011 and that's where Rob Rodriguez, a sports-memorabilia dealer in Reno, Nev., bought it all for $4,000.
"I was just flipping through eBay's sports-memorabilia section when I noticed this stuff," said Rodriguez, 54. "I said, 'Wow, this looks great.' "
Exactly how valuable Rodriguez's mementos will be to collectors and historians isn't entirely clear. He has seen almost none of the 16-millimeter films, and the paper records are being examined by a Mack biographer in Texas.
At the very least, though, the treasure trove figures to shed light on how Mack and the original A's owners, the Shibe family, transformed one of baseball's greatest dynasties into a team that in its last 20 Philadelphia seasons finished last or next-to-last 14 times.
The paperwork spans the years from 1915 - two years after Mack's club had won a third World Series in four seasons - to 1954, when the woebegone franchise was sold and relocated to Kansas City. The A's moved to Oakland in 1968.
There are 1,700 pages of handwritten ledgers on salaries, business expenses, concession deals; hundreds of blank checks, including dozens that had been signed by Mack's son, Earle; and, most intriguingly, 15 canisters of 16-millimeter film.
"I've had some health issues," Rodriguez explained this week in a telephone interview, "and I've had a tough time finding a 16-millimeter movie projector. A local photographer had one, but before we could watch them, it broke. I did get to look at one, though. It was fascinating."
After the intervention of the Philadelphia A's Historical Society and Mack's grandson, Connie Mack III, a former U.S. senator from Florida, the records found their way to Texas author Norman Macht, who is completing a massive, three-part biography of Mack.
According to Macht, the ledgers detail just how successful the Athletics were until 1932, when they began selling off the best players from one of the best teams in baseball history.
While the A's were flush enough to issue $600,000 in dividends from 1921 to 1931 (with $300,000 going to Mack himself), as the Great Depression worsened they fell off a financial cliff.
Macht, whose second book in the Mack trilogy, covering the years 1915 to 1931, will be released this spring, said the team's financial fortunes mirrored their on-the-field accomplishments.
"The year 1932 was disastrous," said Macht from his home in San Marcos, Texas. "[Revenue from] home and road admissions dropped by about $300,000."
Mack's team played in its third straight World Series - and ninth overall - in 1931. In its remaining 22 years in Philadelphia, the club never reached another.
Over the years, sportswriters and historians had inquired often about the Athletics' Philadelphia records. A new generation of club executives assumed they had vanished.
And until this year, no one had any reason to doubt them.
'Really cool stuff'
Historians such as Macht knew the ledgers existed because not long after the A's were sold to Kansas City businessman Arnold Johnson in 1954, Philadelphia newspapers included several mentions of them and even a photograph.
But Macht couldn't uncover them in either Kansas City or Oakland.
"I found a former secretary who remembered seeing the files in a closet gathering dust," Macht said. "She thought she recalled that during an office remodeling in the 1970s they had been thrown in a Dumpster behind the Coliseum."
She was right. What she hadn't known was that a stadium worker had found them and kept them closeted until, a year ago, apparently in need of money, he brought them to an Oakland flea market.
The man who bought the dusty collection there decided to sell them on eBay, the online auction site.
Rodriguez, as he frequently does, was scrolling through that web site's sports offerings when he spotted them.
"I'm always looking for baseball cards, autographs, really cool stuff," he said. "And this was definitely really cool stuff."
Rodriguez got involved in the 10-day bidding and, for $4,000, won the items.
Looking through it all, he knew the value would be enhanced if he could prove the careful handwriting in the ledgers belonged to Mack, the Hall of Famer who was the manager and/or owner of the A's for all their Philadelphia existence.
He contacted the Philadelphia A's Historical Society, the organization which has a gift shop and library in Hatboro. Society vice president Bob Warrington, an historian and avid collector himself, suggested he contact Macht, whose 708-page first volume on Mack, Connie Mack and the Early Years of Baseball, was published in 2007.
Macht arranged for Rodriguez to send him the files. But weeks later, when he still hadn't received them, the anxious author enlisted the aid of Mack's grandson, who telephoned Rodriguez.
"[Sen. Mack] was wildly interested in the project," recalled Rodriguez, "and he asked if there were anything he could do to help speed it along. I told him I'd been ill, but that I was going to send the books as soon as I could."
They arrived at Macht's San Marcos residence in August and, as he finishes his third volume, the biographer has been studying them ever since.
The papers include a separate page for each of the Athletics, detailing their salaries and financial history. A few pages are missing, Macht said, including the one for Ty Cobb, the baseball legend whose final two seasons, 1927-28, were spent with the A's.
The records span the era in which Mack went from being a minority partner during the reign of the Shibe family to controlling owner. Many of the entries deal with mundane topics such as postage, field supplies, and concessions.
"Until he died in 1937, John Shibe appears to have paid $2,000 - later $3,000 - a year for the concession rights at Shibe Park," Macht said.
He also discovered that Mack, despite getting that $300,000 in dividends during the team's gravy years, only took a modest salary.
"Mack never paid himself more than $20,000 a year, some years less," Macht noted. " . . . When [his sons] Roy and Earle took over in 1951, they immediately [raised] their salaries to $25,000 [each]."
In 1932, the season after their third straight World Series appearance, the A's payroll was $253,000, Macht said, unsustainable in a year when ticket revenue plummeted by $300,000.
Mack reacted by selling players. Al Simmons, Mule Haas and Jimmie Dykes brought $150,000 in 1932, beginning a downward spiral from which the franchise never recovered.
"They still had several hundred thousand in indebtedness to the banks and things didn't look any better for 1933," said Macht. "In 1933, the gate fell by another $200,000."
Facing a loss of more than a quarter-million dollars, the A's that year sold George Earnshaw and future Hall of Famers Mickey Cochrane and Lefty Grove.
As interesting as all that is, it's the 16-millimeter films, which Rodriguez believes may have been shot during A's spring trainings, that could have the most historical and commercial value. Footage of Hall of Famers like Grove, Cochrane, Simmons, Jimmie Foxx and Mack himself is in short supply.
"The one I saw, it was hard to pinpoint exactly when and where it was," said Rodriguez. "But once I get a good long look at it all, we'll know a lot more. I can't wait."
Contact staff writer Frank Fitzpatrick at 215-854-5068, email@example.com, or @philafitz on Twitter. Read his blog, Giving 'Em Fitz, at www.philly.com/fitz.