Your clutch analogy is a particularly good one – let me embellish it further:

I have a Kawasaki Concours 14 Motorcycle. You can easily do 60 mph in 2nd gear on this motorcycle – you can also do 60 mph in 5th gear.

To go 60 mph in 2nd gear you merely give it more throttle. In 5th gear it takes less throttle.

For trumpet playing, shape is the gears, and air is the throttle.

In my estimation, James’ is talking about the more throttle approach. I’m sure when it comes to his own playing, he uses both more throttle and additional gears.