Lydia Ko, David Leadbetter and the blame game

Last week, Brandel Chamblee created a stir with critical comments about golf instruction that appeared in a two-part interview by Golfweek's Adam Schupak on March 24 and 26.¹ In response, instructor David Leadbetter penned a scathing "open letter" to Brandel that was published in Golf Digest on March 27.² That same day, Golfweek's Eamon Lynch chimed in on Twitter with the following Tweet, and David fired right back:
For those unfamiliar with the Lydia Ko-David Leadbetter saga, here is a recap:

By the fall of 2013, 16 year old Lydia Ko was a rapidly rising star in women's golf. In October, she announced her intention to turn professional. At that time she had accomplished the following: youngest person ever to win a professional golf tour event, the youngest person ever to win an LPGA event, and, in August 2013, the only amateur to win two LPGA Tour events. In all, Lydia had won five professional events while an amateur and, at the end of 2013, was ranked 4th in the world in the Rolex Rankings.

Although born in South Korea, Ko's family emigrated to Auckland, New Zealand when she was young. In Auckland, Lydia's instructor was local professional Guy Wilson, who started teaching her at the age of five. However, as a professional, Lydia planned to live in the United States and decided to change to a coach based in the US, selecting David Leadbetter. Reportedly, her family admired the swing of Leadbetter student Hee Young Park. Lydia settled in Orlando, which was also the home of Leadbetter's golf academy.

Ko announced the move to Leadbetter in December 2013, but they did not begin working together until mid-April 2014. Two weeks later, Ko won her first event as a professional, the Swinging Skirts LPGA Classic, and moved up to number 2 in the Rolex Rankings. For the full year, Lydia won 3 times in 26 starts, placed 3rd on the money list, 3rd in Rolex Player of the Year, 3rd in the Race to the CME Globe and won the Rookie of the Year title. Ko finished fifth in scoring average and ended 2014 still ranked number 2 in the Rolex Rankings.

In 2015, Lydia won 5 times in 24 starts and moved to number 1 in the Rolex Rankings. She finished the year first in most major year-end categories and awards: money title, Rolex Player of the Year and Race to CME Globe, and finished second in scoring average.

In 2016, Lydia won 4 times in 24 starts and also captured a silver medal at the 2016 Olympics. Despite amassing by mid-July commanding leads in all the major year-end categories and awards, Ko slumped badly during the final four months of the season and failed to win any, finishing second in the money title, Rolex Player of the Year, Race to CME Globe and scoring average. David Leadbetter was fired after the season ended. 

This table summarizes the standings in official money, Rolex Player of the Year and Race to CME Globe at July 18, 2016; Ariya Jutanugarn would overtake Lydia and win all three:

After earning an average of $150,000 per event through mid-July, Lydia's money winnings dropped 80% during the rest of the year, to about $26,000 per event:

In scoring average, Lydia had almost a one stroke per round lead over eventual winner In Gee Chun; her stroke average increased about 1.3 shots per round during the collapse:

Critics of David Leadbetter contend that swing changes he implemented were behind Lydia's 2016 collapse. Specifically, changes that were intended to add driving distance without sacrificing accuracy backfired, and caused Lydia to lose both distance and accuracy.³ That, in turn, hurt her greens hitting ability.

David Leadbetter has steadfastly refused to accept blame for Ko's collapse in 2016. He has offered two explanations in interviews and postings on his website (for her part, Ko has not endorsed either explanation):

1. following the Olympics in August, Ko was exhausted, and her poor play thereafter was the result of fatigue, not unreliable swing technique; and

2. Lydia's meddling parents.⁴

However, an examination of Lydia's ball striking statistics lends support to Leadbetter's critics. The LPGA publishes with each tournament's results ball striking statistics for the event for each player, including average driving distance, fairways hit percentage and greens hit in regulation percentage. Those statistics have been collected for each LPGA tournament Lydia played in 2014, 2015 and 2016. To smooth the raw data, a moving average trendline was applied, averaging the statistics for the previous eight events. Below is Lydia's average driving distance during the three year year period; a linear trendline has also been added.

Despite Leadbetter regularly making claims that Lydia's driving distance had increased substantially, the three year trend is definitely downwards. Leadbetter's swing changes did not add distance; to the contrary, Lydia's average driving distance declined on his watch (note: the following post has been deleted from the Leadbetter Golf Academy website):

Similarly, Lydia's driving accuracy and GIR percentages showed persistent declines; in addition to the moving averages, a linear trendline has been added for the fairways hit % data.

The data shows that Lydia's ball striking was well into a sustained decline at the time of the Olympics. The decline was also well underway when Leadbetter took an enthusiastic victory lap in an interview with The Golf Paper's John Huggan published April 27, 2016:

Why, many asked, was she messing with a formula that was so ­successful?

“There was some pressure on me when we started to work together,” ­acknowledges Leadbetter with a smile. “She was very young – she still is of course. But if there is a time to make changes, 16 is that time. But it was still controversial. People were ­asking why we would change anything in a swing that had already been so ­successful.

“When Lydia came to me first she was hitting nearly every shot left to right. She couldn’t move the ball right to left. So that was limiting her game. And she wasn’t as long off the tee as she could be. Now she is maybe 20 yards longer than she was back then. And she can hit a draw, without losing the ability to hit that safe fade. Her swing is also more ­efficient. There is less wasted motion. And we haven’t touched that beautiful rhythm she has.

“Lydia now has a golf swing she can use for a long time. I smile when I look back at all the ­questioning. On ­television, (golf broadcaster) Judy Rankin was asking why we would change anything, which was fair enough. But now Judy is saying that Lydia has one of the best swings she has ever seen and a perfect model to copy. I take that as a huge compliment.

“Lydia is actually the perfect model for what I call the ‘A swing’."⁵

Losing both distance and accuracy is a very potent combination for a professional golfer, and not in a good way. Although the LPGA does not publish it, a total driving statistic was created using the available average driving distance and fairways hit % data. Lydia Ko's ranking in each category from 2012 through 2017 is shown below:
In response to Eamon Lynch's Tweet that Leadbetter is "still blaming Lydia Ko’s decline on her parents," David replied "results are plain to see sadly." Indeed the results are plain to see: shorter and less accurate driving; for Lydia, the "Lead-Death."

Below is for those who prefer to view the statistics in a tabular form. Note that offsetting the decline in ball striking, at least for a while, was marked improvement in sand saves (attributed to assistance from Ernie Els) and putting.

1. https://golfweek.usatoday.com/2020/03/24/brandel-chamblee-bitch-slaps-instruction-exclusive/; https://golfweek.usatoday.com/2020/03/26/brandel-chamblee-qa-part-ii-fixing-jordan-in-2-seconds-questioning-rickies-coaching-change-praising-tiger/

2. https://www.golfdigest.com/story/david-leadbetters-open-letter-to-brandel-chamblee-youre-better-than-cheap-shots

3. https://www.stuff.co.nz/sport/golf/86265170/lydia-ko-may-be-changing-more-than-just-her-caddie

4. https://www.golf.com/tour-and-news/david-leadbetter-says-split-with-lydia-ko-was-bit-of-a-shock; http://www.espn.com/espnw/feature/22858141/how-golfing-prodigy-lydia-ko-lost-way; https://leadbetter.com/lga-news/the-grass-isnt-always-greener/; https://www.reuters.com/article/us-golf-newzealand-ko/new-zealands-ko-needs-break-from-golf-says-leadbetter-idUSKCN1UW0RV

5. https://www.thegolfpaper.co.uk/featured/1907/kos-a-smiling-assassin-says-world-number-1s-coach/