Golf Analytics

How Golfers Win

Expected Tournament Wins

I first discussed the concept of expected wins in my March article on Rickie Fowler over at NoLayingUp. Basically, I wanted to look at how often a certain level of performance on the PGA Tour results in a win. This way, there’s some sort of context neutral benchmark when we talk about why certain players are winning more or less than someone thinks they should. Rickie Fowler was the perfect introduction to this topic; he had been slammed for several years for only winning once on Tour, but when viewed through the lens of expected wins, Fowler had played some really good tournaments that would’ve normally resulted in wins, but others beat him. Of course, Fowler has gone on to win two high profile tournaments already this season

Calculation of Expected Wins

I gathered all PGA Tour tournaments (2010 to present) from the Official World Golf Rankings site, noting the winners and each player’s performance in strokes versus the field (also adjusted for strength of field so the US Open credits players for a harder field and Mayakoba debits their performance). I did the same for all European Tour tournaments over the same time period. I discarded all tournaments that did not reach four rounds and all players who missed the cut or withdrew.

I then performed a logistic regression of performance in strokes per round on the binomial variable of whether the player won the tournament or not. This produced the curves below for the PGA Tour and European Tour. I should note, I included all tournaments in each Tour’s data regardless of whether they were co-sponsored, alternate field, limited field, invitationals, or majors (majors and WGCs were included only in the PGA Tour dataset). However, this is supposed to measure how often a player should win in a typical event. Obviously the listed figure for win expectancy will be lower for majors and higher for alternate field or limited field events like the Tournament of Champions.

PGA Tour results

PGA_Tour_Win_ExpectancyIn a typical PGA Tour event, it’s extremely rare to win with a performance less than 3.0 strokes per round better than the field. However, increase to 4.0 strokes and a player is expected to win just over half of the time, while victory is nearly guaranteed at 5.0 strokes per round better than the field. In fact, only Louis Oosthuizen at the 2012 Deutsche Bank has exceeded 5.0 strokes per round without winning.

The best performance in a tournament between 2010 and 2015 was Rory McIlroy’s eight shot victory in the 2011 US Open where he beat the field by 5.7 strokes per round.

European Tour results

European_Tour_win_expectancyThe curve for the European Tour is broadly similar, but the 50/50 point is reached earlier – around 3.5 strokes per round – indicating the average European Tour event is won with a slightly less impressive performance. In fact, at around 4.0 strokes per round a player would be expected to win a typical European Tour event about 80% of the time versus 50% in a typical PGA Tour event.

The best European Tour tournament between 2010 and 2015 was Sergio Garcia’s eleven shot win at the 2011 Castello Masters.

Best Results from 2010 to 2015

bestperformances20102015Only PGA Tour or European Tour events from 2010 to present.

Applying to Rickie Fowler…again

What’s interesting about Rickie Fowler’s success this season is that both of his wins have come in big events with quality fields, but have required less impressive performances than normal. His Players Championship victory was actually slightly less impressive than his 2012 loss to Matt Kuchar, while his Scottish Open performance earlier this month rarely results in victory – even on the European Tour. In other words, after getting the short end of the results for the first few years of his career, Rickie’s gotten some good luck and has taken advantage of both opportunities to win this season. Below are Rickie’s ten best performances of 2010-15.



3 responses to “Expected Tournament Wins

  1. Ben September 22, 2015 at 10:43 AM

    Nice work. How did you plot the yes/no coloured points, over the logistic regression curve? Do you have the R code? Cheers, Ben

    • jalnichols September 23, 2015 at 10:47 AM

      I loaded data that had the fields: (name, tour, rounds, win, strokes) where win was 1=yes or 0=no and strokes was the average strokes better/worse than the field per round in each tournament.

      Load data into ‘all_tournament_data’


      # filter out the data that won’t be used

      pga_data = filter(all_tournament_data, rounds > 3,tour==”USA”)

      et_data = filter(all_tournament_data, rounds > 3,tour==”EUR”)

      # construct the logistic model

      pga_model = glm(win ~ strokes, family = binomial(logit), data = pga_data)

      et_model = glm(win ~ strokes, family = binomial(logit), data = et_data)

      # capture the coefficients

      Int_pga = coef(summary(pga_model))["(Intercept)","Estimate"]

      X1_pga = coef(summary(pga_model))["strokes","Estimate"]

      Int_et = coef(summary(et_model))["(Intercept)","Estimate"]

      X1_et = coef(summary(et_model))["strokes","Estimate"]

      # calculate the expected win probability for each golfer/tournament combination

      pga_data = pga_data %>% mutate(linear = (Int_pga + (X1_pga * strokes))) %>% mutate(exp_win = (exp(linear)/(1+(exp(linear)))))

      et_data = et_data %>% mutate(linear = (Int_et + (X1_et * strokes))) %>% mutate(exp_win = (exp(linear)/(1+(exp(linear)))))

      # plot

      +xlab(“Strokes per Round vs. the Field”)+ylab(“Win Expectancy”)
      +ggtitle(“Win Expectancy by Performance – PGA Tour 2010-2015”)

      +xlab(“Strokes per Round vs. the Field”)
      +ylab(“Win Expectancy”)
      +ggtitle(“Win Expectancy by Performance – European Tour 2010-2015”)

  2. jason July 6, 2016 at 4:14 PM

    Very interesting, is there any chance you still have the numbers showing the % chance of winning and shots better than field? Would love to see the numbers all the way through….

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