GvA's interview has a different tone / message: he says he is good but didn't have the chance to show it. He is not so much pointing to other riders, but more to his bad luck with regards to crashes, putting too much effort in his futile breakway and the lack of opportunities to go in the right
No way his better values are worse than Cavendish, he is just exaggerating and there is no way he did his best numbers in these conditions.
GvA saud he pushed his best 10 minutes wattages and was in the last group (on saturday, the interviews was before the stage on sunday).
This could indicate the level is high, but there are many factors at play: if you invest your energy to get the breakaway going, but the peloton isn't easing up, you can easily push your best numbers with no chance on getting away, while some minutes later, the right breakway can happen because the dynamics of the chase are different.
With all of this, I don't want to say that it's nothing of an indicator. If TdG states he is being dropped by 70 riders after having done a very good 10 minutes effort, it is a kind of alert. Ofcourse, it is one for TdG in the first place, and he seems to draw conclusions for his own career. But it's also a good indicator of what's happening in the peloton.