This year, for only the third time in the team’s existence, the Houston Texans’ defense is ranked higher than the their offense.

I won’t bore you with details you’re already well aware of, but to summarize: new defensive coordinator Wade Phillips has turned coal into diamonds, with a little help from J.J. Watt, Connor Barwin, Johnathan Joseph, Danieal Manning and DeMeco Ryans.

Despite not having superstar pass rusher Mario Williams, who was lost five games into the season to a torn pectoral muscle, they rank second in yards allowed, third in points allowed, second in yards allowed per play, second against the pass, sixth in interceptions, seventh in sacks, first in opponent passer rating (after being ranked dead last in the same category last year), and fifth against the run.

That’s why some figured the Texans might be able to survive the loss of key offensive cogs Matt Schaub, Matt Leinart and Andre Johnson, two of whom (the Matts) are out for the remainder of the year. And they might have been right, because while he’s not exactly lighting up the league, rookie quarterback T.J. Yates has been decent as the starting quarterback and the offense has continued to produce to a satisfactory level.

Unfortunately, the defense has started to slide.

Oh, what timing.

Although they’ve only given up 13, 10, 19 and 28 points since Schaub went down, the numbers and the eyeball test indicate that they’ve fallen off a tad.

And while a “tad” might not be the same as a “bunch” it still might be enough to derail a depleted team.

Aside from his two picks, Yates was relatively solid Sunday against Carolina. Good enough to beat a bad team if your defense is elite, which Houston’s supposedly is. But the Texans were pushed around by the Carolina offense, especially down the stretch. Ultimately, the back-breaker was that they allowed the Panthers to convert nine of their 14 third down attempts, which is pitiful.

Part of the problem could be the pass rush, which has just three sacks in the last three games after recording seven in Week 12 against Jacksonville. Could the absence of Williams finally be catching up to them?

And what kind of role did not having Wade Phillips in the booth play on Sunday against Carolina? Phillips is away from the team for medical reasons, and he likely won’t be available Thursday night when they travel on short rest to play another potential spoiler in Indianapolis.

Phillips has stated that the game plans were designed prior to his leave, but it has to hurt not having a genius defensive coordinator available as the game develops.

Of course, this could all be an anomaly. Even the best defenses go through bad stretches, and the numbers don’t indicate that there’s a serious problem in Houston. But with the AFC playoff race jumbled and injuries severely restricting the offense, the margin for error defensively is low.