"These are very strong bikes, but they still have to push 220-230kg uphill. So to keep good momentum through the corner is very important, otherwise you lose a lot of time on the exit. You have to be very careful with the throttle.
"Also here, I think Casey [Stoner] was the first one last year, he was stepping out the rear and using the inside kerb to widen the track a little bit and keep the momentum."
Turn three is also a good test for the traction control.
"If you are playing with the traction control this is a very nice place to look, to understand the way the traction control interferes with the engine.
"There you go. You can hear nearly nothing [cutting out] on the Yamaha. It's not electronically controlled anymore. Before you had ignition cut, the 'da-da-da-da' sound. That kind of stuff is already nearly gone out of MotoGP. You just hear the bike smoothing out now.
"The bike gives the most power it thinks that the tyre can have at that point, but of course lean angle, speed and throttle position - everything is included in the calculation. It can be really important to see what problems they have with it here."
For the riders, body position is crucial in terms of anticipating problems and keeping the machine under control.
"The riders have to be prepared to open the throttle, let the bike spin-up and make sure that if something goes wrong they are able to 'swallow it' [correct it], body-position wise, before it becomes a big problem.
"You can see Bradley [Smith] is getting there with his body position, he just needs the finishing touch.
"Cal [Crutchlow] is more at ease compared with two years ago, when he was very excited and you can see that in his riding style."
As other bikes lapped the track, Zeelenberg added: "That was Bradl. You could see that the tyre was used a lot and you cannot have the same momentum as with a new tyre. With a used tyre you have to close the throttle into this corner.
"The Ducati is sliding a lot... The Yamaha looks controlled... That CRT bike is spinning too much, but it looks nice sideways!
"Overall this is a good area to spot any problems - and one problem they all have now is that it is starting to rain!"
It was time to head back to the pits.
Thanks again to Wilco Zeelenberg for the insight.