It’s not every day you see someone trade in a whiteboard for a wedge and end up hoisting a green jacket. But that’s exactly what Michael Greller did when he walked away from a decade-long career as a sixth-grade math teacher and became the full-time caddie for Jordan Spieth—arguably one of golf’s brightest stars of the last decade.

Since teaming up in 2011, Greller has been Spieth’s steady presence through soaring highs, gut-wrenching lows, and everything in between. He’s been there for every defining moment—from Spieth’s wire-to-wire win at the 2015 Masters to that unforgettable fairway bunker shot at the 2017 Travelers. But before Greller was calling yardages and reading greens, he was leading classrooms and grading homework in Washington State.

So, who exactly is the man behind Spieth’s bag? Let’s take a look at the remarkable journey of Michael Greller, golf’s most unlikely—and arguably most respected—caddie.

Greller’s journey from the classroom to the course

Michael Greller didn’t grow up dreaming of the PGA Tour. Born in Michigan and later based in the Pacific Northwest, Greller pursued education with full intent. He graduated from Northwestern College in Iowa and went on to earn a Master’s in Teaching from George Fox University. For ten years, he taught sixth-grade math at Narrows View Intermediate School in University Place, Washington.

But even as a full-time teacher, Greller harbored a side passion for golf. He wasn’t just a weekend player—he was a fan, a student of the game. In 2006, that fandom quietly turned into something more. During a U.S. Amateur Public Links event, he noticed a young player named Matt Savage carrying his own bag. Greller, never having looped before, offered to caddie for free. Savage shot one of his best rounds, and Greller was hooked.

From that point on, he began volunteering as a caddie during his school breaks, carrying bags for elite amateurs including Justin Thomas and future U.S. Amateur champ Kelly Kraft. Still, he remained a full-time teacher, sneaking in caddie gigs like most people sneak in side hustles. That all changed in 2011, when Greller was asked to loop for a 17-year-old Texan named Jordan Spieth at the U.S. Junior Amateur. Spieth won the event and a loyal caddie in the process.

The Spieth era: From teen prodigy to tour champion

Greller’s life took a dramatic turn after that win at the Junior Am. He and Spieth stayed loosely connected over the next year, working together again at the 2012 U.S. Open. When Spieth turned pro later that year, he made a pivotal call: he wanted Greller on the bag full-time. The offer came from Jordan’s father, Shawn Spieth, and while Greller had already taken a sabbatical from teaching, the idea of quitting altogether felt massive.

“I was hesitant,” Greller admitted in a Golf.com interview. “I loved teaching. But Ellie [his wife] just looked at me and said, ‘You’ve got to do it.’” He never looked back. By 2013, Greller and Spieth were full-time partners on tour. That season, Spieth won the John Deere Classic, played on the Presidents Cup team, and was named PGA Tour Rookie of the Year—all with Greller quietly steering from the sidelines.

The duo’s defining stretch came in 2015, when Spieth won both the Masters and the U.S. Open, came one shot shy of a playoff at The Open Championship, and nearly captured the PGA Championship. It was the kind of run that turns good golfers into legends—and caddies into fixtures. At the Masters that year, Greller helped Spieth stay grounded during a turbulent moment on the 17th hole. “He’s great at settling me down,” Spieth said afterward. “He’s the calming voice in the storm.”

Perhaps their most iconic moment came two years later. At the 2017 Travelers Championship, Spieth holed out from a fairway bunker in sudden death. The celebration that followed—a full-on running chest bump between Spieth and Greller—is etched into golf history. But Greller is more than just Spieth’s hype man. Behind the scenes, he’s known as one of the hardest-working caddies on tour. He dives into stats, course conditions, and strategy with the kind of precision you’d expect from a former math teacher. He’s even been known to study past caddie notes, consult with course veterans, and pore over putting green tendencies during practice rounds. “Everything I did in the classroom—managing stress, reading people, adapting on the fly—it all applies out here,” Greller once told The Seattle Times. “Except now I’ve got one big kid instead of thirty.”

Their relationship goes beyond business. The two are friends, brothers even. They tease each other about college sports (Greller is a Michigan guy; Spieth bleeds Texas orange), and they share the kind of shorthand communication that only comes with time and trust. Even through Spieth’s struggles—the winless stretches, the swing tweaks, the mounting pressure—Greller never flinched. “He’s the most competitive guy I know,” Spieth has said, “but he never shows it. That helps me more than people realize.”

In 2024, when Spieth was sidelined due to wrist surgery, Greller temporarily looped for Max Homa at The Sentry. It was a rare break from their otherwise constant partnership, but as of early 2025, Spieth is on the comeback trail—and Greller, of course, will be right there with him. Away from his professional charm, let’s look at what parts of personal life Greller chooses to share with us.

The man behind the bag

Away from the cameras, Greller keeps a low profile. He lives with his wife Ellie in the Seattle area and still speaks fondly of his teaching days. He’s private but grounded, a man of deep faith and loyalty who prefers fishing over flash. He doesn’t do a ton of interviews, but when he does, he talks more about gratitude than glory. “The last thing I want to do is be part of the story because it’s about Jordan,” he recently shared with Golf.com. “Frankly I don’t like to talk about my story ’cause I’m fortunate just to be riding along with Jordan.” 

He’s become an unintentional symbol of what can happen when you take a leap—when you trust your instincts, work hard, and stay humble. That’s why, even after three majors, 13 PGA Tour wins, and countless clutch moments, Greller still gets emotional about the game. “I cried after St. Andrews in 2015,” he once admitted, referencing Spieth’s narrow loss at The Open. “I cared that much. Still do.”

So, who is Michael Greller? He’s a teacher who took a chance. A math guy who found meaning in the messiness of professional golf. And perhaps most of all, he’s proof that sometimes the smartest plays don’t come from a playbook—they come from the heart.