Houston is a tough team in general, no doubt, and a good road team to boot. But Atlanta has shown flashes of competence of late, and getting them in the +175 range at home has good value.
This is a good example of a game where the market in general is skittish about putting money on such a crappy team as Atlanta, and that is what maintains value in these kids of situations (the same sorts of things happen in baseball as well, where the worst teams in the league often have the best returns at home of any team in the league). But Atlanta is at home, and Houston is not an elite team. A line this big has value.
Thanks GG, I agree with you that ATL is Johnson and a bunch of scrubs, and that Hou is significantly better than ATL even without Yao. But the eternal question is, where is the value? And here I don't think Hou's superiority over ATL's scrubbiness merited a 60+% likelihood of getting a road win. As a general rule of thumb, only elite teams in the NBA deserve to be road faves of as great a margin as Houston was here (see the Phoe/Minn game tonight as an example). Sure Houston could have won by 5, but 50% of the time? And they could easily have won outright, but 62% of the time? That's a tall order to fill, and one that in general should usually only be granted to the handful of elites in the league each year (Phoe, Dal, Sant).