Obama came out soundly for Perez, you just missed it.
I listened to extensive interviews with both Perez and Ellison, both seemed fine to me although I slightly favored Ellison (even though I think Bernie was a hopeless cause celebre). It's nice that Perez is bringing in as his deputy.
If the election cycle taught us anything, it is that the chairman for either the Dems or GOP is a toothless tiger. The next election cycle around the Dem establishment is going to be playing catchup with their base. Who the chair is is pretty meaningless.
All in all I'd have to agree with one talking head I saw on CNN who likened this election to the world's biggest high school student council president election.