Should I Leave the Flagstick In Or Out?

During the 2023 Michigan PGA Professional Championship, I was playing with two other pros and we got to chatting about the flag stick. One of the guys I played with said you should leave it in and that he tells all the members at his golf club to play accordingly. I, on the other hand, recalled from the research that I did that it's better to leave it in.

So, which is it?

I've been having fun with ChatGPT lately. I decided to put it to the test to see what it says.

Question 1

My first question was:

What does the research say on whether or not you should leave the flagstick in in putting in golf?

It told me:

As of my last update in September 2021, the question of whether or not to leave the flagstick in when putting in golf has been the subject of debate among golfers, especially since the 2019 update to the Rules of Golf allowed players to leave the flagstick in the hole during putts.

Here's a brief summary of what research and anecdotal evidence suggest:

1. **Effects on the Speed of the Ball**: Studies by golf publications and independent testers have found that a putt struck at a high speed is less likely to drop with the flagstick in. For putts traveling at fast speeds, the flagstick can act as a barrier that prevents the ball from going in.

2. **Effects on Direction**: For off-center hits, the flagstick can either help or hinder the ball from dropping. If a ball is going slightly off-center, the flag might redirect it into the hole. Conversely, if it's going significantly off-center, the flagstick might keep it out.

3. **Type of Flagstick**: The type and thickness of the flagstick can make a difference. Some tests have shown that thinner flagsticks are more forgiving, whereas thicker or more rigid flagsticks can act more as barriers.

4. **Psychological Effects**: For some golfers, having the flagstick in can provide a psychological benefit. It might serve as a better visual reference, helping players aim and judge distance more effectively. For others, it might be a distraction.

5. **Downhill Putts**: Anecdotally, some golfers feel that leaving the flagstick in for downhill putts is beneficial, as it can act as a backstop for faster-moving balls.

6. **Convenience**: From a pace-of-play perspective, leaving the flagstick in can speed up the game, especially for longer putts where players would otherwise walk up to remove it.

In conclusion, the decision to leave the flagstick in or out during putting largely depends on individual preference and the specific circumstances of the putt. Factors like putt speed, angle of approach, hole position, type of flagstick, and personal comfort can all play a role. Some golfers may choose to always leave it in or out, while others might make the decision on a putt-by-putt basis.

Question 2

I revised and said:

Thanks. Let’s not consider convenience or psychological effects. I’m just interested in pure data from testing. Can you answer more objectively?

It said:

Certainly. Based on pure data from testing conducted up to September 2021:

1. **High-Speed Putts**: When a putt is hit at a pace that would send it several feet past the hole (if it missed), the flagstick is generally more of a hindrance. Data suggests that a fast-moving ball has a higher probability of bouncing out with the flagstick in compared to it being out.

2. **Off-Center Hits**: The flagstick can sometimes assist slightly off-center hits. If the ball is just missing the edge, a flagstick might redirect it to drop in. However, for balls moving significantly off-center, the flagstick can act as a barrier and prevent the ball from falling in.

3. **Type of Flagstick**: Tests showed that the effect of the flagstick can vary depending on its thickness and material. Thin fiberglass flagsticks were found to be the most forgiving, allowing more balls to drop than if they were out. On the other hand, thicker and more rigid flagsticks tended to repel balls more frequently.

4. **Downhill Putts**: For downhill putts that tend to pick up more speed, having the flagstick in can be beneficial. The flagstick can act as a backstop, slowing down a fast-moving ball and allowing it to drop. However, if the ball is moving at a very high speed, the flagstick may still repel it.

To sum it up: For putts that are hit firmly or are moving downhill quickly, the flagstick can sometimes be beneficial but can also hinder if the ball is moving too fast. The effect is also influenced by the type of flagstick used. For slower-moving putts or those hit directly at the center of the hole, the presence of the flagstick tends to have a lesser effect on the outcome.

Question 3

Based on that, I asked two more follow-ups. I wanted to ask about slow moving putts in particular because I like to hit putts at about 2-3 revolutions per second approaching the cup speed, which is fast enough to get it there but slow enough to not have a big testy comeback putt. That speed is such that the ball falls deep in the cup and take full advantage of the full width of the hole.

Objectively, is it better to leave it in or take it out with slow moving putts?

For slow-moving putts, objective tests up to September 2021 generally showed that the flagstick has a minimal effect on whether the ball drops or not when hit directly at the center of the hole. However, if there's any variation (i.e., if the ball approaches slightly off-center), the flagstick might increase the chance of the ball dropping in.

So, based purely on data, for slow-moving putts, it's slightly advantageous to leave the flagstick in.

Question 4

Objectively, is it better to leave it in or take it out with fast moving putts?

Objectively, based on testing data available up to September 2021, for fast-moving putts, it's generally better to take the flagstick out. Fast-moving balls have a higher probability of bouncing out with the flagstick in compared to it being out. So, for putts that are hit with a pace that would send them significantly past the hole if they missed, removing the flagstick is advantageous.


So, there you go…ChatGPT's answer for whether or not you should leave the flag in when putting.

For me personally, I like to have it out, assuming it's not leaning towards me or one of those super thick flagsticks. I like the visual frame of reference, particularly on long putts. I also hit my putts at a slower speed.

What do you like?

A Look at My Lag Putting

Here is a current snapshot of my lag putting over the last 2 weeks...50 randomized putts from each distance with no 2 putts being the same and no distances repeated twice in a row. Average distance of all 3-putts was a little over 50 feet.

A Look at Jaacob Bowden's Lag Putting Stats