I would start with strike; make sure you're hitting down on the ball a few degrees, reasonably out of the middle of the club head, and with reasonable control of face to path.
I recommend at least one hybrid. Hybrids will launch higher and with more backspin, so they will have a better descent angle. They also appear to maintain ball speed better. I carry 2 hybrids--3h and 4h; love them. Be sure to hit down on them and take a nice divot.
Pro golfers generally don't maintain a cap and I assume your friend created the info as a hobby.
But I kinda question the accuracy of the info.
In 2019 (from lpga.com), Jin Young Ko had a fantastic year on the LPGA and was the scoring avg. leader at 69.062.
I realize scoring avg. might not have a 1:1 linear relationship to cap because the pros play different events vs other pros on a week to week basis, (some pros sitting out event), each course has a different rating/slope, etc, etc.
I did some eye balling on info on results on lpga.com......there was a period where JYK on her best 10 of 20 had a total of 657...I also eyeballed results for Nasa in her best 10 of 20 rd period and got 660....yet the info from your friend says Nasa had a best/lowest cap in 2019 of +5.5 vs, JYK's +4.5.
Only as a FYI........I believe during the above period...JYK's highest score in those 10 rds was a 67 and Nasa's was 68.
But IMO an glaring potential lack of accuracy is for Anna Nordqvist who as per the above chart has a similar best and avg 2019 cap as JYK.
Just eyeballing a best period/run for Anna in 2019....it's difficult to find a best 10 of 20 where there are a lot of scores in the 60's and was 2.4 strokes higher in scoring avg at 71.471 (T65) vs. JYK's leading 69.062.
I didn't quit when I played Chambers Bay. I played it right before the 2015 US Open. Loved every minute of it. While the conditions were close to what they had at the Open, I played from further up tees ("sand" if I recall correctly). The hardest thing that took getting used to was how the fairways and greens were non-distinguishable. I generally aim for the middle of the green on most approach shots unless I have a 9i or less, so it was hard to do that there.
However, your point is well-taken.