first off people seem to forget that two important things were said on the nature of curse seals in this episode.
1. Sasuke has a level 1 seal
2. lvl 2 is much stronger then lvl 1 but hurts the body more and most likely doesnt look like anything the jounin has seen before. also is it just me or does at least 2 of the guys look like they have bloodline limit.

the 4 sounds used lvl 2 seal against 2 tired jounins. The 4 sounds are not that powerful they were used by oro to be shields and stuff. oro wouldnt want any strong jounin around so he needs to train genin and brainwash them to follow him thus no strong jounin.