AI Scoring Difficulty

I've been playing on the default PGA Tour Season Settings; by default the AI Scoring Difficulty is set to 50. I've also been playing with the default Tour Difficulty settings - not sure if that impacts the AI Scoring Difficulty as well?

Anyway, I am about 1/4 through the career season and the best AI score at the end of a tournament seems to average around -15; the peak I've seen so far is -21. How much better does the AI get when you set the AI Scoring Difficulty to 100?