So? All records fall eventually. Stoner beat everyone on the grid that is racing today, the same people Marquez is beating. I believe Marquez is a better racer, but I don't think his outright speed is much greater. The way they both dominated race weekends from practice until the checkered flag on Sunday is very similar. MM is having a season like Stoner did in 2007.
And they were all around the same age and fitness then. Marquez has that edge of a few less years and a few less screws and plates and a few less concussions. Not to say he didn't knock himself almost out of a career because almost did. Keep in mind J Lo and Pedro have taken some HARD licks in the past few years. Relatively speaking Rossi and Marquez are the two fittest front runners imo. Injuries add up and Dani and J Lo have an extensive list. I don't care how good your physio is, some days you're gonna feel that stuff.
As has Bot, J Lo, VR, MM, etc... From week to week one person will beat the other, happens all the time...