Ok, I've had many different jumpers....jags, largemouth, dempsy's, SH's.....here's the deal.
If you pick him up and he's already so dry he's not plyable....he most likely, 99%sure, he won't make it unfortunately. I've picked them up with all sorts of dry skin and stuff on them and what not but the ones who make it are usually still movable. Next time this happens hopefully you catch it sooner and.....grab his ass by the bottom lip like a bass and get him ripping through the water to rehydrate the gills hard and fast and get the flow over them. After that get him protected and somewhere that he won't be bothered. Thats all I've got....hope it helps in the future.
The only thing I've ever put back in that was stiff was a pleco and he was back to normal, kinda, in about 10 min.