It seems, Watier ("count Wathier") was replaced with Sebastiani in Wilna on 29 June 1812, to become commander of a cuirassier division, for having showed his incompetence by some inapt manoeuvers:

https://books.google.de/books?id=DLpXAAAAcAAJ&pg=PA206

I don't know which cuirassier commander was replaced by Watier, and why it is less disadvantageous to have cuirassiers manoeuvered badly.

Starklof gives two different sources for this allegedly ungraceful transfer, but still the reasons given could be just a baseless rumour.