Normally, puberty doesn't take more than three years, but MLS' extended puberty as it reaches the peak of its teenage years is hitting a high point this off-season. For what is likely to be the final time in the league's history, the league lost a team in Chivas USA, and that along with an expansion of two teams next year made it necessary for a couple of teams to be shifted.
According to MLS' press release on the situation, the Houston Dynamo and Sporting Kansas City will be the teams shipped out West to accommodate for the now vacant slot in the conference and the addition of Orlando City SC and New York City FC in the East.
Though Houston are a team in flux at the moment with Dominic Kinnear moving back to San Jose, SKC are the reigning MLS Cup champs for at least a little while longer and will bring a style of physical soccer into the West that most other teams in the conference don't play. It's safe to say that the West just got a bit harder to make the playoffs in.