Their "average distance" on tour is skewed down by the fact that it's an actual round of golf and may require a cut, might hit a tree/rough/bunker or possibly they use less than driver. All that said, a solidly hit persimmon isn't that far behind a modern driver.
I plan to "prove" my theory this season, as I play in a charity tournament that requires the winner of the long Drive contest to use their shitty old persimmon driver on the of hole the next year. Im going to give it my all to take that title again and really leave them wondering what went wrong. The only problem with the plan is I will need the wind to stay down on the day, 2 years ago I was to the hole fairly early in the day and hit a bomb riding the wind a little and got out over 350 yards... the wind came up another 15+ mph later in the day and a guy I routinely out drive took the contest. If that happens, I won't be able to do anything about it, but on a level playing field, I think I still can win.
Side note brag- I have personally eagled that LD hole every year I have played that tournament, all in my own ball. Good things happen when you go for broke in the tee and hit the fairway! It's not a crazy difficult hole, just over 500 yards, but a massive upslope to drive on to, fairly simple green. Anyway, I look forward to it every year.