Never said that is best burst barb can do but if you dont know that it is nice burst than you need to try it.
I tried every possible pvp build on barb and know what dmg it can dish. Personally i prefer zerker with upheaval and hybrid build with 3 points in AM,but deacp build can also be pulled off i just dont like loosing anti cc.
But since you laughed at my post lets do quick math:
rampaging horde and thirst for blood up, knock finisher 700 dmg, staggering blow III 1.7k, finishing blow 1k+, ATG 1.6k and decap 1.8k-2.1k, that is all with non crit on most targets except heavy.