Get over the "physical fitness" thing.
Yes, the players are more conscious of diet and strengthening than they were, and it's got to help some, but it CAN'T POSSIBLY explain the amateur situation.
I can hit it 30 yards further today at age 33, than I could when I was 21, played three different sports and played golf three times per week as opposed to once a fortnight now. I can't touch my toes now, wheras I could run a 2hr 47 min marathon when I was 21.
My 64 year old father (plays less than once a month and shoots high 80s) hits the ball 15 yards further than when he was a 25 year old 3 marker.
The Prov1x comes out, and a number of the guys I keep in touch with from my caddying days like Peter O'Malley swear it has added another 10 yards on to the ProV1. I got 10 yards out of ProV1 and another 5-8 out of ProV1x.
And don't start me about playing with my current driver and fairway woods compared to almost brand new clubs from the early 80s. Another 15 yards without blinking.
My original home club has had to move three fairway bunkers back to keep them in play, and we are talking members, not pros. Middle aged, once a week, no warm up members. They neither are in better shape than before, nor are they aware of any diagnostic technology or more likely to take a lesson. They've simply traded in their Titleist DTs for ProV1s, and their Honma wooden drivers for a Warbird or Taylor Made V Series.
BALL: 45%
MODERN METAL WOODS: 55% (includes shaft, head etc)
COURSE CONDITIONS: immeasurable, since just as many are more lush and soft as there are those which are firmer. My old club now has automatic watering and plays softer all year
LAUNCH MONITOR: Most golfers have never availed themselves of this technology
PHYSICAL CONDITIONING: What a joke. Australian and American societies are more obese and out of shape than at any time in the past, so quit citing that as a factor. For Pros only, maybe 10-15%, thus slightly reducing the effect for them of ball and clubs.