Only Rabbainu took on Uman

HH 25 Tishray, hillula of Rabbi Levi Yitzchok of Berditchev.

The Berditchever came to Uman to be the Rabbi of the city, and the residents - the leading "maskilim" (enlightened - apostate Jews who swore never to even mention Gd lest they have remorse) came to mock him in his face. The holy Berditchever couldn't even look at them, because it is forbidden to look at the wicked, and they continued to ridicule him and mock him out of the city.

When Rabbainu came to Uman he reversed the tables on them and had them eating out of his hand, and they began to repent and return to Torah observance.

Rabbainu's main disciple - Rabbi Nussun, was not either able to deal with apostates, and we don't find anyone in Breslov (and certainly not from anywhere else) that was able to deal with apostates until Saba Yisroel Dov Odesser who easily slid into this position found only by his master Rabbainu Na NaCh NaChMa NaChMaN MayUMaN.