Protholy pallies atm are running with around 30k unbuffed even with just a so-so setup, while still pushing 3k unbuffed SP. see:
The World of Warcraft Armory for a not even all that great example. And that guy is in PvE gear mostly gemmed and enchanted INT (except his pvp pieces), which gives no spellpower benefit to a prot build.
It is kind of broken, because all you do is stack stam stam and more stam (a 30 stam gem gives you 9.x sp...).
On the other hand, it hinges entirely on teammates which are able to live and win high end arena matches with 0 instant healing and 1 second+ cast time heals that crit for 5k tops on an MS'd target.
It doesn't seem overpowered to me, given how much skill that takes to work out in the days of the most retarded damage since ToEP+ZHC stacking got nerfed, but I haven't arenad for a long time.
I can see how being able to stack pure 30stam and get the same spellpower out of gems as another healer stacking pure purple sp+15 stam gems can seem unfair, though.