What went wrong? Defensive line

The only position coach retained from Gary Kubiak's staff was defensive line coach Bill Kollar, which speaks in part to how his unit performed.

Thus, we reach our first part of the "What went wrong?" series in which we discuss a position at which not a ton went wrong.

We began this series two weeks ago and should wrap it up by the end of this week. Already analyzed positions include safeties, running backs, inside linebackers, receivers, outside linebackers and tight ends.

Today: defensive line.

Key players: J.J. Watt, Antonio Smith, Earl Mitchell, Jared Crick

What went wrong: As we discussed last week in the post about the Texans' outside linebackers, Houston's interior pass rush, with Watt and Smith, was their strength.

James Palmer from CSNHouston.com caught up with new Texans defensive coordinator Romeo Crennel at the Senior Bowl today, for an interview that will air at 6 p.m.. Crennel had this to say about Watt: "If we had 10 more like him we'd be pretty good. He has a motor. He's got good ability and range. Those type of things are important and I think he sets an example for the other members of the team as well."

Watt's versatility was important for the Texans, as was Smith's skill. Neither of their sack numbers reached last year's level, but they were still disruptive on the field. Watt actually made a higher per-play impact in 2013 than he did in 2012, according to Pro Football Focus, despite having less gaudy numbers with 10.5 sacks and seven batted passes as opposed to 20.5 sacks and 16 batted passes.

As for Mitchell, he was an upgrade over Shaun Cody, who was the Texans' starting nose tackle during the 2012 season, but the 3-4 defense might not be Mitchell's best fit. His quickness could be a better fit with a 4-3 defense and Mitchell will have the chance to explore that this offseason as he hits free agency. Smith is also set to become a free agent.

Reason for hope? Absolutely. Watt could be the only starter who returns to the defensive line next season, but he's the most important one. A young pass-rusher added to the line would benefit from his example and tutelage. He was a guy who talked about the lack of accountability with the Texans in December, and one who can help make sure that changes.