A funny thing happened at the 2014 Arnold Palmer Bay Hill Invitational. Not one player who started round three outside the top 10 moved into the top 10 by the end of the day. Round four saw five players who started outside the top 10 move into the top 10. But wait, isn’t the third round supposed to be moving day, when players scramble up (or down) the leaderboard to position themselves for final-round contention? The phrase is firmly etched into golf’s lexicon, but is moving day real or a myth?
To measure leaderboard volatility, I looked at changes in the top 10 players at the end of each round for all 460 four-round events from the 2008 season through this year’s U.S. Open. I define “turnover” as the fraction of new players at the top of the leaderboard after the round compared to the beginning of the round. The results? The average turnover was 41 percent in round three and 35 percent in round four. Given the number of events analyzed, that’s a concrete and significant difference. The ’14 Palmer was an anomaly. Stats prove the moving day effect is real.
Lower Scores = Volatile Leaderboard
What explains the volatility? Do players take more risks on Saturday and play more conservatively on Sunday? Does pressure lead to higher Sunday scores? Perhaps. But I think the explanation is related to the effect of course setup on scoring. Because stronger players are more likely to make the cut, you’d expect lower scores to be posted on the weekend, even if course conditions were comparable across four rounds. Using strokes-gained analysis, it’s possible to disentangle the strength of the field from course-difficulty effects. Weather is a big factor in course difficulty, but Mother Nature doesn’t know the day of the week, so weather effects average out over a large sample, leaving course setup as our focus. Based on ShotLink data, round three proves to be the softest course setup of all rounds, playing 0.3 strokes easier than round four, the toughest scoring round.
Combine that observation with this: It’s slightly harder for the best players to separate themselves from the pack in easier scoring conditions (round three) than in tough ones (round four). I looked at the round-by-round average strokes gained of the eventual event winners and found that they gained nearly the same amount on the field in rounds one, two and four (3.9 strokes per round), but in round three gained 0.3 strokes less (3.6 strokes per round).
Easier course setups in the third round lead to a smaller scoring advantage, which in turn sparks leaderboard volatility. And what do you call that whole lotta shakin’ goin’ on? Moving day.