You start Houston's defense. You have to. You are making the wrong comparison. Only compare the Houston Defense to any other defense you can potentially play. If you think the Houston defense will score the most point of these defenses, then you play the Houston defense.
You cannot worry that you have a WR on the other team and "hope" the Houston D takes a week off. It would be nice, but It doesn't work that way.
14 team ppr auction league:
ALL TD's 6 pts, std scoring w/PR&KR.
QB: Flacco, Cassell
RB: Sproles, Charles, Jackson, Brown, Dwyer, Best
WR: Harvin, Marshall, Cobb, Maclin, Colston