[Closed] Are my hub's bearings goosed? Dead Mavic?

I have a pair of Mavic Crossmax XL wheels. In recent weeks, before the Mayhem mudbath (!) the LBS serviced the bike and fitted a new cassette, chain, chainrings etc.

I am guilty of jetwashing the bike after Mayhem and leaving it to fester in the garage. However on a ride earlier this week I was concerned that on any fast downhill bits when I'm riding 42-11 there is just no pick-up from the drive train ... I need 2-3 very fast crank rotations to get any torque and pick up from the cassette (it used to be instantaneous).

Have the bearings given up? Any advice appreciated - thanks!