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Monthly Archives: July 2014

British Open 2nd Round – Tee Time Adjusted

In yesterday’s 1st Round the morning wave benefited from calmer conditions, with the earliest off gaining around 2.5 strokes on the latest tee times. Notably, 15 of the 18 to break 70 were in the morning wave. Unfortunately for that afternoon wave, the morning on Friday was the harder half of the draw. Winds passed 15 mph, calming to around 5 mph by the afternoon, meaning early morning players played in conditions around 3 strokes more difficult than the latest afternoon tee times. Each hour on Friday was worth around 0.3 strokes the earlier your tee time was. Cumulatively between Thursday and Friday, the golfers with the easiest course played in conditions 3.1 strokes easy than the hardest conditions. However there was little difference within waves. Everyone teeing off on Thursday from 11:26 AM local time onward lost between 1.3 and 1.6 strokes to average and everyone teeing off before that gained 1.3 to 1.6 strokes to average.

Only four of 23 players within 10 shots of the lead went off in the late Thursday/early Friday wave. That includes only one player (George Coetzee) in the top ten.

The R&A has decided to send golfers off two tees Saturday morning, reducing the expected difference between the earliest tee times and latest tee times to less than a quarter of a stroke (provided the weather remains similar to what we’ve seen thus far). That’s great for fairness, though forecasted wind is less than 5mph for all hours of play tomorrow.

Tee time adj 2nd round

Does High Ball Flight Hurt at the British Open?

During the coverage of The Open Championship on ESPN I’ve heard numerous references to how a high ball flight hurts a golfer (because it exposes the ball to the wind longer) or how golfers have to adjust their ball flight lower to avoid the wind. The conventional wisdom certainly makes sense here, but I’ve never actually looked at it. If it does make a significant difference then guys like McIlroy, Fowler, Jason Day, Stenson, etc. who bomb it high would either have to adjust their games or suffer the penalty. To test whether this is actually happening I’ve taken the PGA Tour’s posted Trackman data on Apex Height and used the results of the past six Open Championships to measure whether there is any connection.

Design Assumptions:

1. That a golfer’s ball flight with their driver, woods, irons, etc. is represented by their Trackman Apex Height measured only on drives. My limited knowledge of projectile physics and golf confirms this is likely true.

2. That a golfer is hurt by either 1. high ball flight or 2. adjusting their game away from normal high ball flight. It may be that high ball flight harms golfers at The Open, but golfers easily compensate for it without harming their ability. It seems unlikely, but keep in mind I’m not compensating for whether golfers play differently at The Open.


The PGA Tour has radar measurements since 2007. My Apex Height for each golfer is simply their average of the two prior seasons (or one prior season if they have only one). I’ve tossed out anyone without listed data; this removes most European Tour golfers. This is unfortunate, but there’s no data available (and it avoids confounding the results with any home continent advantage).

To judge performance I simply compared each golfer’s performance relative to the field in that year’s Open Championship to what I expected from them entering the event, using my ratings up to the date that tournament was played. These ratings are heavily based on the previous couple of seasons of overall performance. This allows me to measure performance changes¬†due to the impact of ball flight. A golfer who performs to expectation will receive credit for no change, while one that overperforms by a lot will be credited for overperforming. I’ve used Open Championship results from 2008-2013 because that’s when there is Trackman data available.


First, ball flight is strongly correlated between seasons for golfers. Season N is correlated at R=0.77 to Season N-1 and R=0.68 to Season N-2. What Apex Height measures is definitely a persistent ability for golfers.

Apex Height British Open

It appears that a high ball flight does not impact performance in The Open Championship positively or negatively. This is based on 437 tournaments over 2008-2013.


The results indicate there is no impact on performance, however some caveats are needed. 1. This assumes that the randomness of putting has washed out of the results. Golfers have hot or cold putting rounds all the time which are not impacted by ball flight at all, and I cannot be certain this hasn’t impacted the results. 2. This also assumes that weather effects have been distributed evenly. It seems unlikely that the high ball flight golfers have benefited from disproportionately calmer weather conditions, but weather is highly variable and the sample is only 437 golfer tournaments.

Despite those caveats, I think it’s likely that either high ball flight doesn’t harm a golfer’s chances at The Open or that golfers can modify their ball flight at The Open without seeing any negative impacts on performance.

First Round Review – 2014 Open Championship

Really fantastic first day of competition at Hoylake leaving a leaderboard stacked at the top with the best in the world (Rory, Sergio, Adam Scott, Tiger). Haven’t seen much in terms of stats anywhere, though the course played to around 73.5 (+1.5 to par). Almost all of the very best scores came from the early wave with only three players breaking 70 in the latter half and fifteen breaking 70 in the morning half. I’ve adjusted the scores for ability (using my ratings) and tee-time in an attempt to measure how everyone would’ve played if they had theoretically teed off at the same time. Rory still comes out looking best, but Adam Scott and Shane Lowry both look much better relative to the rest of the top 10. The chart is linked below and shows that for every hour a golfer teed off earlier than 11:15 EDT the course was 0.25 strokes easier and later than 11:15 EDT 0.25 strokes harder. That ~2.5 strokes difference is largely in line with more mild past British Open rounds (more extreme past rounds got up to 6-8 strokes between early and late tee times.

The real question is what the weather will be like tomorrow, especially whether it will change. The R&A’s insistence on sending everyone off the first tee means weather exacerbates tee-time based differences in course difficulty. Typically courses play easier in the morning because they’re softer and the greens haven’t been walked over as much. They get harder in the afternoon as the greens firms up and get walked over by a couple hundred people. The Open adds the variable of wind to the equation. If early conditions tomorrow are windy, it could cost the late Thursday/early Friday group a couple of strokes relative to the early Thursday/late Friday group – definitely enough to cost Adam Scott and others a run at the Claret Jug. The forecast tomorrow calls for the wind the be strongest around the early morning tee times (~17 mph) while weakening into the afternoon (~11 mph). That’s in line with what occurred today however, meaning it doesn’t look like conditions will differ much between the earlier and later groups.

british open 1st round

Your live-scoring destination for the weekend is Ken Pomeroy’s awesome automated Twitter feed @KenPomGolf.


EDIT: Now that I have seen basic field stats (61% GIR, 63% Fairways, 281 yards off the tee) I can say there’s nothing that interesting going on here stat-wise. Scrambling came in at only 50%, which is low compared to PGA Tour average.

Performance Impact of Playing John Deere Classic vs. Scottish Open

The week before The Open Championship features a choice for the elite golfers on the PGA Tour; they can enter the John Deere Classic, a weak field PGA Tour event with the smallest purse of regular full-field events, they can take the week off to prepare for The Open Championship, or they can enter the Scottish Open, one of the premier European Tour events held on a links style course which exempts the OWGR top 60 – giving PGA Tour golfers a chance to play in Europe. This week, in addition to golfers who actually hold European Tour cards, Phil Mickelson, Rickie Fowler, Jimmy Walker, and several others all chose to tee it up in Scotland, while Jordan Spieth, Zach Johnson, Harris English, and most others entered the John Deere Classic.

The arguments in favor of entering the Scottish Open are two-fold in my eyes: first, you get to acclimate to the time difference a week before many of the other golfers, and second, you get to play a links style course rather than a typical PGA Tour layout which presumably better prepares you to play the following week. Phil Mickelson famously won the Scottish Open last summer, before winning his first Open Championship at Muirfield the next week. As a bonus the Scottish Open purse is the same size as the John Deere Classic (£3,000,000 vs. $4,500,000).

As to the advantages of playing in the John Deere? First you accumulate FedEx Cup points to either secure your card or bolster your chances of advancing further in the Playoffs. The PGA Tour awards no points for guys playing in Scotland. That obviously goes for the exemptions that come with winning the tournament as well. It’s possible that certain players couldn’t secure entrance to the Scottish Open, but it exempts the top 60 in the World Rankings. Spieth, Zach Johnson, English, Ryan Moore, Kevin Na, Chris Kirk, Kevin Streelman, and John Senden all could’ve entered but chose to play in Illinois. As a bonus, the John Deere provides a Sunday night charter that transports golfers from Illinois to Britain.

When I tested my assumptions that playing the Scottish Open the week before was an advantage my results indicated that golfers who played in Scotland rather than Illinois the week before enjoyed a significant advantage relative to those who played in the John Deere. I’ll explain my process and results below.

First I gathered the results of the last six Open Championships that I had handy for another project. I then found basic performance expectations for each golfer with results based on their prior performances (basically using results from the two years prior to each Open). That gave me results to compare and a baseline of expectations. If players significantly over or underperformed that baseline in each Open, that likely indicates playing the Scottish Open or John Deere the week before was a better strategy. I then gathered data for the prior week, finding who played in Scotland or Illinois.

My results were very convincing that playing the Scottish Open gave a player an advantage. On average, golfers who played the Scottish Open performed around 0.65 strokes/round better than those who played in the John Deere, relative to their baseline expectation (John Deere players were around 0.9 strokes worse than expected and Scottish Open players were around 0.25 strokes worse than expected). I had 144 players in the John Deere sample and 310 in the Scottish Open sample. The results are below denominated in strokes compared to PGA Tour average; negative numbers indicate performance better than average and in the difference column positive numbers indicate worse performances.

british open prep

The results were consistent in each of the six seasons I examined. Players who played the Scottish Open always were advantaged over those playing the John Deere, by between 0.2 strokes/round to 1.5 strokes/round. I ran simulations using the baseline expectations, normal observed standard deviations, and the sample sizes from the last six years. The simulations showed a difference of the size measured in favor of the Scottish Open players less than 1% of time. Based on the size of the effect and the fairly large samples for both tournaments, I think it’s very unlikely this is simply variance.

My current methods don’t allow me to completely tease out what factors are contributing to that advantage. The group of golfers who played neither event the week before underperformed their expectation by 0.43 strokes (compared to 0.83 for John Deere and 0.25 for Scottish Open). Mixed in that are golfers who competed elsewhere in the world the week before The Open (Asian Tour, Japan, etc.), golfers who arrived in Britain for prep the same week as the Scottish Open and didn’t compete anywhere, golfers who arrived in Britain at the same time as the John Deere competitors, and European based golfers who didn’t compete anywhere. All this indicates is that there appears to be some advantage to playing the Scottish Open and some disadvantage to playing the John Deere classic.

Perhaps there is some residual home continent advantage to getting used to the time change over the course of ten days, rather than three. Perhaps the value of an extra week preparing on a links course is actually sizable. There’s also the fact that most of the sample of Scottish Open players are regular European Tour players with slightly more experience playing links style courses. While I don’t think overall experience plays much of a role in this difference, it’s likely a small factor. It’s clear however that something is causing players from the John Deere to dramatically under-perform relative to those who are playing in the Scottish Open. In future seasons PGA Tour players qualifying for the Scottish Open would be better served taking advantage of the invitation in order to better perform the following week.