Since Ken Roczen and Ryan Dungey were neck-and-neck the whole race at Arlington, I wanted to do one more check on "how much do riders slow down throughout the race?" (Follow Up #1 looked at some of the "non-elite" riders.) From what I can see, 4 main variables affect how much riders slow down throughout the race: endurance (i.e. riders getting tired), track deterioration, getting stuck behind other riders, and riding conservatively because they're too far behind to catch up and too far ahead to get caught. In the case of Roczen vs Dungey at Arlington, we can remove #3 and #4 because neither was ever stuck behind other riders and they were both going 100% the whole race from start to finish.
How Much Slowing? -- Follow Up #2
Ken Roczen and Ryan Dungey, lap times at 450SX Arlington 2016
In the original article, we determined Dungey slowed down around 0.05 seconds per lap on average. Since then, at San Diego 2, where Dungey lead fairly comfortably from start to finish, he slowed down by 0.11 seconds per lap. At Arlington, on the other hand, he slowed down by 0.03 seconds per lap.
Roczen, in the original article, was determined to slow down by 0.07 seconds per lap on average. At San Diego 2, Roczen slowed by 0.06 seconds per lap (0.056, if you expand one decimal place). At Arlington, however, he only slowed by 0.05 seconds per lap (0.048, expanded one decimal place).
So both Roczen and Dungey slowed down less at Arlington, which is as we would have expected, though I figured that there would be a bigger difference compared to each of their averages.