Reasons Why Average Driving Distance Is Now Over 290 Yards

[Keefer]

To what extent has average clubhead speed increased for tour pros?

My guess would be 5% or less over the last 40 or 50 years - and that fairly modest increase has to account for all of the incremental increases attributable to the usual suspects - lighter, longer shafts; lighter clubheads; more forgiving clubheads; bigger, stronger athletes; better mechanics; and of course competition.

I would tend to agree. I remember seeing where Bobby Jones clubhead speed was ~ 113 mph. If you've ever seen some of the old Shell Wonderful World of Golf shows you'd see some 300 yard drives. I would also agree that course (grass) conditions have a big influence as well. If you go to any PGA Tournaments you'll see fairways that look like some muni courses putting greens. I remember going to the Transitions Tournament in Palm Harbor FL. and seeing the grounds crew roll the fairways.