Buried deep in his analysis of Rory McIlroy's equipment switch and the initial criticism is this nugget from Larry Dorman, former Callaway SVP.
It involves the longtime rumors of Callaway paying off Phil Mickelson's purported gambling debts, and is preceded by an apology from Dorman for inserting himself into the story, who then explains what went into vetting Mickelson before his signing with Callaway in 2004.
If this doesn't put those rumors to rest...
Phil had won 15 tournaments, including the 2004 Masters, during his successful affiliations with Ping and then Titleist. He was ranked No. 4 in the world on the Official World Golf Ranking, his Titleist contract was expiring, and he was considering his options with other manufacturers. The month before the Ryder Cup was to be played at Oakland Hills, he signed with Callaway, swayed by the company’s new golf ball and driver combination. The surprise signing and the proximity of the Ryder Cup combined to cause quite an uproar in the media.
Baseless rumors arose in some quarters, questioning Mickelson’s motivation for signing. When I say baseless, I mean totally unfounded, manufactured rumors alleging gambling debts that had no basis in fact. Mickelson did like to gamble at the time, but he had zero outstanding debts and his betting patterns -- a stat that Vegas casinos keep -- had him even, to slightly up. All the information was checked out by Callaway’s head of investigations, a former head of counterintelligence for the U.S. Army, and no evidence was found to support the claims, either of gambling debt or any other charge.