Jordan Spieth's caddie made about $2.1 million this season, more than 221 PGA Tour golfers

Jordan Spieth had one of the best seasons in PGA Tour history, and, as a direct result, so did his caddie, Michael Greller.

In 25 events, Spieth won five times (including two majors) and finished in the top-10 a whopping 15 times. That added up to more than $12.0 million in official PGA Tour earnings. However, once we include Spieth's win at the Hero World Challenge and his $10 million bonus for winning the FedEx Cup, prize money that is not counted on the official money leaderboard, Spieth's 2015 earnings surpass $23.0 million.

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, including 10% for the FedEx Cup bonus, Greller's cut this season would be $2.1 million.

That would be enough for Greller to rank 39th on this year's PGA Tour money least, ahead of 211 PGA Tour members, and just behind Phil Mickelson ($2.2 million).

For comparison, Tiger Woods made just $448,598 this season.

Assuming Greller is paid using the standard caddie rates, the only question would be the $10 million FedEx Cup bonus and whether he will indeed receive a $1 million (10%) cut. Last year, Billy Horschel gave his caddie a full 10% cut of the bonus. Presumably, Spieth, who is a big believer that golf is a team sport, will do the same.

Greller quit his job as a teacher in 2013 to caddie full-time for Spieth. He is probably happy with that decision.