I don't know the patience rating, maybe 80+, as I never demote anyone I value. You could try DFA, without waivers assuming your player has an option, and leave him there for 15 games or so. Then put him back on the BL team while your fill-in does the work.. I've never tried it but it feels like a workaround to me. The pitcher you DFA will not recover from fatigue while in limbo.