"Improbable"? That's about a one in twenty-five thousand chance. 12 successful saving throws is about one in 500, and 8 or 9 failed Ref saves is also about one in 500 (give or take). The odds that BOTH are true? One in 25000.
Dude, I've personally had 2 dice rolling sequences (for 2 different PCs in 2 different games) that involved probabilities that were literally longer odds than winning the Texas Lottery. One was a string of 8+ consecutive natural 20s, the other a similarly long sequence of natural 1's with a percentile die thrown in the mix in which I succeeded on everything but a "00"...and rolled "00".*
The thing is, we're talking long odds...but they're spread out over 30+ years of gaming, over tens if not hundreds of thousands of die rolls.
As for corroborating evidence, how, on the Internet, could I possibly supply any? Even if I did get the other participants in those events to take the time to join ENWorld and address your specific concerns, they could be dismissed as being me with additional accounts.
* FWIW, both incidents have been recounted here on ENWorld.