Jon Super/AP
In 19 events so far this season, Spieth has 12 top-10 finishes and five wins, including the Masters and U.S. Open. That has added up to $9.7 million in winnings and $8.7 million on the official Tour money list*. The latter is more than twice as much as anybody else on the Tour this season, and already more than any golfer has ever won on the regular portion of the PGA Tour schedule.
Caddies are traditionally paid 5% of the prize money for making a cut, 7% for finishing in the top-10, and 10% for winning a tournament according to Golf Digest's "undercover pro." If Spieth is using the same structure, his success on the golf course this season translates to a share of $866,534 for Greller. That would be enough for Greller to rank 93rd on the PGA Tour money list this season, ahead of 159 PGA Tour members.
Greller quit his job as a teacher in 2013 to caddie full time for Spieth. He is probably happy with that decision.
Business Insider
* Jordan Spieth won $1 million for finishing first at the Hero World Challenge. While it is an official PGA Tour event, the winnings do no count towards the official money list as there are so few players who compete (18 this year).