While there does seem to be some semblance of the old Patriots teams in the sense that they aren't making mental mistakes and the Chargers are, we're clearly seeing the team miss Randy Moss. Welker isn't getting even 1/4 of the looks he used to when Moss was here and the Chargers are able to rush Brady more now that they don't have to worry about a deep threat.
That's not to say they can't overcome that. Hernandez, Gronowski, and Tate could all emerge more over the rest of the season and the return of Fred Taylor will eventually help.
Still, it's clear that Moss leaving isn't "no big deal."