It depends on how they lose.
If Portland just shoots lights out from the perimeter (possible) then there won't be that much blame. It's like would anyone blame the Clippers if they lost to GSW because Curry and Thomspon go nuts? I wouldn't... you can't do much when you're contesting and the guy is just hitting bucket after bucket in your face.
If Houston loses because McHale makes terrible calls at the end of close games or puts bizarre line ups on the floor, then Dwight won't take as much blame. If Harden is a no show in multiple games, Dwight won't take too much heat.
As long as Dwight plays solidly I don't think he'll get too much blame, especially with this being his first year in Houston. I'm sure Barkley and Shaq will go ballistic for him not "taking over", but blaming a guy who's been clearly playing worse over the last 3 years vs his time in Orlando for not playing at a MVP level isn't something most fans will hold too much against him.
Now if Dwight plays like crap, expect the media to go nuts on him. As for fans, outside of Lakers, Houston and Orlando fans, I think most of the NBA fans are somewhat indifferent.
J.R. Smith: "They were pretty much scoring at will. Especially my guy. I don't know what the hell I was doing on defense."
Raymond Felton : "The play was give the ball to Melo."