1) People were less active - seems supporters of mr Ušakov (Saskaņa) were less active, probably just tired (as most of them like Ušakov because of free public transportation in Riga).
2) People have approved policy of current coalition. Even if Vienotība has lost 1/3 of their supporters, still, coalition seems strong as never before.
3) People are getting smarter. New and old messiahs (like "No sirds Latvijai" or "band of ex-premiers Vienoti Latvijai") that come with message of "saving the nation" seems not working any more so well.
4) People are afraid in current geopolitical circumstances and were voting for parties that were supporting increase in defence (NATO) spending.
5) Overall, vote was still for personalities (Artuss Kaimins #1 in Regionu Apvienība, Solvita Aboltina out of Vienotiba list etc), not programms. As expected.