Putting with the flagstick in could be a mistake, new Golf Digest study from Cal Poly professor shows

The question over whether you should putt with the flagstick in has sparked plenty of debate. The one thing missing until now has been any real science.

Partnering with California Polytechnic State University-San Luis Obispo professor Tom Mase, a Ph.D in mechanical engineering and a member of the Golf Digest Hot List Technical Advisory Panel, we sought to find out if it is in fact true that putting with the flagstick in is always better than not. While Mase’s research is preliminary, the takeaway is pretty clear: The benefits of the flagstick are at best inconclusive and may in fact prevent off-center putts from going in more often than they would if the flagstick were removed.

In other words, hold on to your DeChambeau.

(Bryson DeChambeau, you’ll recall, seemed fairly unequivocal in his assessment of golf’s new rule that allows players to leave the flagstick in while putting. He said in January at the Sentry Tournament of Champions: “After the testing we’ve seen, and what we just did out there now, absolutely, I’m going to leave it in. I’m going to do it until I can see that it messes me up. For the most part, we’ve seen it to be a benefit and not a detriment. That’s from anywhere.”)

Mase’s study, conducted at Cal Poly’s golf practice center at Dairy Creek Golf Course with help from men’s coach Scott Cartwright and women’s coach Sofie Aagaard, used a putting device called the Perfect Putter to roll putts at a speed slightly faster than minimum holing speed. (The theory being that holing speed, approximately two-and-a-half feet past the hole, is not affected by the stick being left in the hole.) The Cal Poly study examined straight and breaking putts that crossed the hole at the upper third, the middle of the hole and the lower third.

Mase released a video of the test conducted last week.

The results showed that with a breaking putt entering the hole from the low side, keeping the flagstick in prevents some putts from being holed. With the flagstick out, those putts are holed every time.

The study also showed that the coefficient of restitution for the flagstick is relatively low, and that direct impacts with the stick, regardless of the type, tend to stop the ball fairly quickly, helping it to finish in the hole every time at a speed that sends the ball five to seven feet past the hole. Further tests of the different flagsticks showed that fiberglass sticks—those most commonly used on the PGA Tour—were the most forgiving, but while multi-diameter and tapered aluminum pins rejected putts that otherwise would have been made, even the fiberglass pin caused more putts to have been missed than were made with the flagstick out.

Off-center flagstick strikes on the low side of the hole tended to shoot the ball off farther away, hence the problem with balls rolling toward the hole on the low side.

Still, for putts entering on the high side, leaving the flagstick in wasn’t such a sure thing, either. While nine out of nine putts were made with the flagstick out, each of the three types of flagsticks yielded less than perfect results for high-side entry putts. For the multi-diameter aluminum stick, there were only seven makes. Same for the common fiberglass flagstick. But for the tapered aluminum stick, it got worse: only two of the nine putts were holed. That’s a difference of 78 percent between flagstick out and flagstick in.

In an earlier test from a longer distance, Mase found that straight-in putts were made 100 percent of the time with both the flagstick out and the flagstick in. On low side entry, putts were holed 80 percent of the time with the flagstick out, but only 56 percent of the time with the flagstick in.

Mase, who will continue to run further tests on the flagstick-in/out question at Cal Poly’s golf practice center, found the testing results surprising, given the current attitudes some tour players have expressed.

“While the sample is very small on this data, I believe it represents well what is happening here,” he said. “Low-side putts will definitely be hurt by having the pin in. Putts entering the center will be made with or without the pin. High side entering putts is a little bit of a pin type dependent problem. However, high-side hole entry without the pin performs best.

“The results are intriguing and perplexing. At first, I bought into the pin helping always. But it is too easy to set up a low-side entering putt that is made 100 percent without the pin and not close to 100 percent with any of the three pins tested.”

Your move, Bryson.

Source: Golf Digest

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