OK, not really in that order but basically this is the chain of events:
SRAM Red RD/1091R chain and Ultegra 6600 cassette on a wheel used on a trainer. Everything was working great through the winter. First nice day out I put on a set of Mavic Ksyriums with XG-1090 (the training wheel is an Aksium btw). Shifting is sub par, sluggish going down into higher (smaller) gears, a little noisy, but not jumping gears. Dropped it off a a LBS after the ride, they tweaked the cable tension, I took it for a spin around the parking lot a few times, wasn't perfect still and as it was getting late I left it there.
Fast-forward to today. Picked up the bike, didn't ride it there given that I was wearing dress shoes and such after work. I don't consider the shop incompetent btw so I assume everything was good to go. Although they comment was made about best they could do given its Cervelo and SRAM. I am not sure what that really meant since the shifting had been perfect at one point or another. In any case, came home, switched in the training skewer (not the wheel/cassette, didn't even take the wheel out. Put the bike on the trainer, looking forward to an hour of Sufferfest. Rear gears jumping around, won't even stay in 28. WTF?!
So, the question is, if you are still reading , would changing the skewer somehow screw up the adjustment on the rear derailleur? I didn't touch limit screws, cable tension, b-screw. None of it. So, poor adjustment in the first place or what???