It all adds up. I tend to think my drive train is about 5-10W less drag at 300W than other race bikes I come across.
All guessing based on the number of bearing cartridges, the force on the bearings, and just feel and experience.

My guess is the BB is good for 2W, the chain 4W (PTFE or waxed, vs std lubed), the freewheel 2W, pulleys <1W, pedal bearings 3W... Any number could be challenged. But when I put it all together, I get an <12# bike reported to feel faster under power.
So happens it will be doing a Pikes Peak test ride in about 2 hours. If it is raining - ride is off, can't take the risk of getting those bearings wet. By no means am I'm saying they are "better" just that I do think the friction is a bit lower. RPM for cycling is so low, I think the precision part is less a deal than most say.