I'm with Gun rod bow on this one. For the most part those fish that are jumping around violently are spawned out bucks that are trying to rid themselves of parasites and/or fungus.
If it is a chrome fish it could be jumping for joy but more often than not it may have a hook stuck in it's back. At some areas like pools below dams and hatchery intakes I see nice chrome fish cavorting about and I think it is just a nervous response due to overcrowding in the hole. If there are chinook present in the same pool they will keep the steelhead sulking near the tailout. Case in point, Rivermill Dam.
On the Deschutes while us FF'ers are waiting for the light to leave the water we will see steelhead porpoising and breeching in the soft water, gradually moving up to the top of the run.
I've tried to fish over them when they are doing this to no avail, gotta wait until they hit the moving water and feel aggressive again.
Just my observations........