I think the Texans face a major uphill climb to win. Their 2016 track record just does not suggest they are a potent team. However and to be fair to the situation, their path to making it a game and pulling off the upset is: Patriots have shown, at times, pass D softness up the short to mid middle. I'm guessing that's been their overall softest D spot. Brock O stays patient and takes those passes whenever they are there, even if it's only a few yards on some passes/don't force it, they will move the ball into Patriots territory. They need to convert one or two of those trips into Patriots' territory as well as rack up a couple FGs. On the D side they pressure Brady often when only rushing 4 -- something that has been the most frequent PO Patriot killer -- and absolutely positively don't let the Patriots convert on their first couple of possessions to jump out to an early lead.
Houston puts that together and they can win. But I'll say this, if the Patriots' pass D plays that middle tough? Ouch for Houston. Their path to victory becomes a much much narrower window toward an unlikely 9 to 6 type score and/or the Patriots shoot themselves in the foot at a level they rarely do.