Earthshield bug or working as intended?

Earthshield procs in my pvp gear are healing for 3600 non-crit on me, however when I use it on someone else, it only heals for 2700 non-crit. I noticed it in BG's and in duels. This is after the +15% talent fix. Is there a reason its lower on other people that I'm just not aware of? Only healing for 75% of its intended value seems like an important bug if thats the case.

note: My dr damage mod that shows what spells should do by using the same spell formulas that blizzard uses, is extremely accurate on every single properly functioning ability and it also shows it should do 3600 ish. So its effect on other players is probably the part that's not working properly.