Did Paladin's healing get nerfed?

I've actually been noticing this for a while but now I've got it confirmed. I think Paladin does not heal as advertised any longer. It says he heals for 40% of his dealt damage, but if I deal 2500 damage I only see him healing for roughly 500 HP which is 20%. That, of course, heavily reduces his usage, and that may be why I have some trouble with him in the new Caves. Can anyone confirm this?