I also like to track stats. I think it's one of the best ways to improve your game ("that which is measured, improves"). I keep a spreadsheet of all my stats, updated about every 50 rounds, and it has helped alot. It got me focused on GIR for awhile, which got me to legend tier. Then I started working on distance to pin and 1-putt %, which has taken me a bit further. Sand saves and scrambling % are also important.
That said, I also notice that driving stats and GIR are also off from time to time, although I haven't seen this on RSG. I'll look out for it, and report if I see the same.
I admittedly don't know Master tees, but do you really use driver on #5? From back tees, I'd want a very strong tailwind to go for that low % shot. I don't think the tee advantage is that great. A layup with 3-wood gives you a pretty good look at birdie. Now, of course, that wouldn't explain the % issue you brought up. Just curious.