By Dan Reardon

In today’s sports world, there is an abundance of data available to measure athlete performance. Sabermetric analysis, which first gained attention in baseball, now pervades virtually every sport. Golf is no exception. With the PGA Tour’s introduction of ShotLink several years ago, you can quantify performance no less than 130 different ways on the Tour’s website.

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What you can’t measure empirically, despite all the data collected, is the one element that separates players at all levels of the game — pressure. Years ago a three-time U.S. Open champion offered me a treatise on pressure in a conversation outside the locker room at Baltusrol. Hale Irwin, a former University of Colorado defensive back — a position played on an island — understood pressure in athletics early.

As Irwin explained, the greats actually relish pressure. It enhances their performance in the moment. He thought the feelings were universal when circumstances intensified, but the successful response was uniquely evoked only by those who thrived.

The last few weeks on the PGA Tour give us a couple of reminders of how pressure alters a player.

At Quail Hollow for the Wells Fargo Championship, 30-year-old Roberto Castro was on his way to his first PGA Tour win, up by two strokes with three holes to play. Bogeys at 16 and 17 dropped him into a tie with James Hahn, and they headed back to the 18th tee. Castro had played the tough finishing hole at 1-under for four rounds in regulation. But when faced with the chance to realize a lifetime dream, he drove the ball into the water left and finished second.

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This past week offered a reprise of sorts with one-time winner Brooks Koepka at the AT&T Byron Nelson. Koepka’s lead had grown to three on the backside when consecutive bogeys at 14 and 15 and a Sergio Garcia birdie at 16 left them tied at the end at 15-under.

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Koepka had navigated the finishing hole at 2-under over the first four trips, but with a win on the line, his reliable fade stayed straight, finding the water. Garcia, a player with a reputation for spitting the bit down the stretch, ended a four-year winless drought on Tour.

Afterwards Koepka explained the errant tee shot in the playoff. “Hit the fade we always hit. Kind of hit it a little bit off the toe and drew back into the water. Against the wind I was kind of hoping it would hit the rocks but it is what it is.”

While a poor shot in a playoff may be a glaring example of the effects of pressure, that same need to perform during anxiety can play out in a broader fashion on Tour. Consider, again, the Nelson and the final round on Sunday.

After three rounds, Koepka topped the field at -16, two strokes clear of a struggling Jordan Spieth. Nine players were positioned to make a Sunday move, sitting no more than five back. The par-70 layout had been handing out rounds in the mid to low 60s for three days. That scoring onslaught continued at the round’s start when Jimmy Walker and Scott Pinckney alerted the field to a great scoring day with rounds of 7-under 63. The prognostics seemed to suggest that the player in the top 10 who could break out would pick up the trophy. The numbers could not factor in pressure.

The same course, on the same day that produced seven rounds of 65 or better didn’t get that performance from any of the first 10 names on the leaderboard. Thirty-seven players posted sub-par rounds on Sunday, but those first 10 players shot a collective 2-over par, with only three players in red numbers for the final round — Matt Kuchar (-1), Tim Wilkinson (-2) and eventual winner Sergio Garcia (-2).

You can give Spieth, who ran out of scrambling magic on the weekend, a pass, but what other consideration is there for the contenders collectively turning into pretenders in the final round? How else do you explain players who had owned the course for three rounds wilting on Sunday? Pressure.

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Dan Reardon has covered golf for radio station KMOX in St. Louis for 32 years. In that time, he has covered more than 100 events, including majors and other PGA, LPGA and Champions Tour tournaments. During his broadcast career, Reardon conducted one-on-one interviews with three dozen members of the World Golf of Fame. He has contributed to many publications over the years and co-authored the book Golf’s Greatest Eighteen from Random House. Reardon served as Director of Media relations for LPGA events in both St. Louis and Chicago for 10 years.