This was also a different type of race than a more typical cobbled classic or really any one day race. You usually see a break or select group getting away inside of 75k to go, and their gap gets pretty cemented because they’ll have good team representation to block behind. Then they’ll start fighting and attacking each other most of the last 20k.
MVDP time trialing on his own is going to have a faster average speed than a lot of those big name break groups. Even though they share the work the attacking and slowing kills the speed so much.
Go to a local crit sometime and see how easy it is for a solo rider to get away when the field won’t work together to put on a consistent chase.
What is believeable is once he had a 2 min lead (and that built up very quickly because no one wanted to get organized or respond) that he could stay way and out TT the chasers. What seems a bit unbelievable was how he was able to put in that attack that built up the lead in the first place. My only explanation is this guy was racing only on weekends and was in no crashes all spring, while others were doing all the mid week races and effectily stage racing all month, while MVdP was weekend one day racing and minimized his work all day to that point. It is the only way I can justify to myself this is a real performance or at least as real as the rest of the field’s “real-ness”. We don’t see MVDP pulling that off in the TdF, but also Tour stages are typically 60kk-80km shorter than classic races, and he has to ride “tomorrow”. In one day, he can wait until the equivalent of a long TdF stage is finish and then launch the pain on everyone else. Maybe he is just better over 6 hrs than over 4 hrs.
RE: How he got the gap - Cobbles are a psuedo-equivalent of a climb. The aero becomes a smaller amount of the total resistance, so the draft is less important. Add to that the tailwind which also makes the draft less significant. But probably the biggest difference is that MVDP could sit 4th wheel through the first 200k with teammates around him going smooth and steady. Even if Peterson and others have teammates around they’re still fighting for position and spending energy in doing so, easier acceleration out of every turn, etc. Reasonable to assume that MVDP hit Arenberg a couple % easier than the rest of the favorites.
RE: Doping and why the results aren’t found in the TdF. He won a stage and took yellow in 2021 and a Giro stage in 2022. He’s unquestionably better at one-day classics but he’s also targeting those races more than TdF stages. I’d rephrase the question and say “Why is the 6-time Cyclocross world champion better at cobbled classics than TdF stages?” That makes the answer a bit more obvious.
Oh and lastly, this year WvA, Tadej, Alaphillipe, and Remco are all either out or non-factors.