Analyzing Nationals to Pac Pacs Improvement


How well did the US team perform at Pan Pacs? There was a lot of concern and speculation over the effects of the long trip to Japan without sufficient time to acclimate to the time change as well as the short gap between Nationals and Pan Pacs. To that end, I thought it would be interesting to look at performance differences from Nationals to Pan Pacs. Pan Pacs is the major international meet of this calendar year, so the goal is surely for the US team to perform at its best there. Did they improve on their times from Irvine in Tokyo? There are certainly many confounding factors, and we have no way of knowing who was rested and to what extent at each meet (although obviously no one is ever rested). To simplify even further, I went ahead and just took the fastest time everyone recorded at each meet rather than just worrying about Prelims vs Finals. This isn’t entirely unreasonable, as for the US, the “B” Final at Pan Pacs is pretty significant too – and even Prelims for some events had the same kind of pressure attached to it!

Just looking at this one pair of meets gives us one data point, which wouldn’t say much of anything, so I also took as comparison the two previous years’ pairs: 2017 Nationals vs 2017 Worlds, and 2016 Olympic Trials vs 2016 Olympics. Sometimes, an image can convey the message quickest. Here is a boxplot looking at the improvement in times from the national meet to the international meet, by year:

A negative number on the y-axis indicates that a swimmer in an event improved from Nationals to the appropriate International meet (the Olympics in 2016, Worlds in 2017, and Pan Pacs this year). In 2016-7, the meat of the distribution is the same: half of the data is from about a -0.72% to +0.24% (that is, a 0.7% improvement to a 0.2% regression). In 2018, this box shifts up by nearly a half percent, having a range of -0.28% to +0.68%.

This year, there were 117 event-swims in common between Nationals and Pan Pacs, with the median time being a 0.2% regression. Just 50 of the 117 swims (42.7%) improved from Nationals to Pan Pacs. By comparison, in 2017, the median time was a 0.1% improvement – with 40 of the 66 event-swims (60.6%) having improved at Worlds. And 2016 was even better, with a median time being a whopping 0.4% improvement – with 31 of the 52 swims (59.6%) having improved.

If instead of looking right around zero change, we took a look at how often swimmers drop a half percent (for instance, Ryan Murphy’s 200 back improvement from 1:54.15 to 1:53.57 is 0.51%), that happened in 20/117 swims this year (17.1%), but 22/66 in 2017 (33.3%) and 23/52 in 2016 (44.2%). It’s not just that people dropped time at all more often in the previous two years, it’s also that they dropped a healthy chunk of time much more often too.

While the headline story of Pan Pacs going away will probably be our performance in the relays, and the commentator’s performance in announcing them, I can’t help but wonder how this meet would’ve played out if we gave ourselves more time in between Nationals and Pan Pacs, or more time to adjust to the time difference. The athletes themselves aren’t making excuses for their personal performances, but maybe we should?

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