WvW Bloodlust buff shouldnt give direct stat boost to players, giving +50/100/150 boost to all stats makes it even harder to get back from losing position. Also this boost makes it hard to organize even GvG matches (having higher stats gives an advantage to team that has it).
In exchange i would suggest to add some kind of boost to siege damage (5% per orb maybe?), reduced damage from siege, damage increase to guards/lords, WExp boost or gold/magic find boost. With this it wouldnt give any advantage in player vs player fights, while giving little advantage for players trying to take objectives like keeps/towers/camps.