1. Conrats! You be run'n with the big dogs now. The same scoring average thing happens to all new Legend tier players
2. I use a base Tournament green speed factor of 1.3 for flat putts over 5 feet but less than 25 feet. Over 25 feet I start increasing the factor - 1.32, 1.35, 1.4, etc.
So I divide the putt distance by 1.3 - 10 feet / 1.3 = a putt stroke strength of 7.7 feet.
For downhill putts the factor gets increased as the grade gets steeper - 1.4, 1.5, 1.6, 1.7 etc.
Some courses, like Merion, have slow Tournament speed greens so for a flat putt you may want to use 1.2 or 1.1 instead of 1.3.
Some tournaments have slower than Tournament speed greens, like this months Transamerica tourney on Congressional.
Use a legal aiming aid for approach shots and reading putts: http://www.wgt.com/forums/t/207460.aspx
Need a smoother meter on the downswing? - http://www.wgt.com/forums/t/207124.aspx
3. So what. Play your own game, and play it 1 shot at a time. If you can hit your longer approach shots closer to the hole than they hit their shorter shots you gain a big psychological advantage.
The bottom line is you have to adjust on each shot for a range of variables - wind, elevation, distance, location of hazards and so forth.
Attention to detail is a key to low scores. Avoiding major errors is a key to low scores. A positive attitude is a key to low scores.
Whack 'em well.