Golf

I just recently started following the PGA Tour, and even more recently started dabbling in betting on golf.

Thankfully, there’s a site called datagolf.com—probably one of the greatest sports statistics and betting sites I’ve come across—which makes it very accessible to get started. They offer live finishing odds for every player in every tournament. For paid subscribers, they even offer betting tools and expected values for various bets using live odds from popular sportsbooks. This makes it really easy to evaluate bets in realtime. (The PGA Tour site, on the other hand, is one of the worst and most poorly-organized sites for stat nerds I’ve ever used.)

The bet I was following on Saturday was the leader Wyndham Clark’s odds of winning. He had a two-stroke lead on the field, which by the end of the round was down to one stroke to second and two-strokes to third.

My philosophy so far has been to put more trust in the players who have been there before as opposed to the newcomers. Whether this is valid or not is to be determined. And Clark, just this past season, had won his first two pro tournaments. Second place Ludvig Åberg had four wins, but just one on the PGA tour, and third place Matthieu Pavon had just one win as well. Further bolstering my confidence was the fact the Clark was playing great golf, posting a 60 in the third round. Perhaps I was falling into the hot-hand fallacy, if that exists in golf.

At the end of the third round, datagolf had Clark’s odds around 29% to win. DraftKings was offering him to win at +200 (33% implied probability). This initally looked like a negative expected value (EV) bet.

Now, my impression of his play that day, his previous experience, and who he was up against bolstered my internal odds to about 33%. But there was one element that was not factored into either of these odds yet: the elements.

The weather forecast for Sunday was dire, with heavy storms throughout the day not expected to let up until the late afternoon. There was a chance they would postpone until Monday, but there was also the chance that the tournament would be suspended entirely. It seemed almost certain that they wouldn’t play on Sunday, but whether or not they would cancel I had no way to know. However, I knew it was at least a possibility, meaning I should bump my internal odds up higher still, turning this into a positive EV bet.

If there was a 33% chance of Clark winning if they played, and a 100% chance of him winning if they cancelled, and a 25% chance that they cancelled, then his win probability should really have been around 50%! This turns into a high EV bet. It appeared that DraftKings, and possibly other sports books, didn’t account for weather and early cancellations in their odds models.

Even if you disagree with my upping the initial odds from 29%, as long as you agree with at least a four percent chance of cancellation given the weather forecast, that puts positive EV on the +200 odds.

At 33% implied odds and 50% actual odds on the current leader, DraftKings was essentially offering people free money.

It’ll be interesting to keep an eye on weather-affected tournaments in the future to see if they’ve learned anything from this situation.