Kansas City, Mo. ? For four games the Kansas City Chiefs were showing big improvement on defense.

Under the direction of first-year Chiefs coordinator Romeo Crennel, the Chiefs held every opponent to fewer than 20 points during a 3-1 start. And that included facing elite quarterbacks Peyton Manning and Philip Rivers.

But then came Sunday’s trip to Houston and a reappearance of the pre-Crennel defense of 2009, the one that finished near the bottom of the league in a 4-12 season.

Leading by 14 points, the Chiefs’ new and improved defense failed to stop the Texans from scoring touchdowns on their last four possessions in a 35-31 loss.

Maybe some fans thought Kansas City’s defense had outgrown such failures. The players knew different.

“I don’t think there’s anybody who’s beyond that,” veteran linebacker Mike Vrabel said. “This is pro football. They’re going to make plays and there are going to be times — I don’t think any defense is beyond that.”

Nevertheless, the defensive collapse was unexpected. It’s the offense that’s been struggling all season, failing to score a touchdown in road games at Cleveland and the Colts.

But the day the offense finally breaks out and scores four touchdowns at Houston, the defense harkens back to 2009.

The Texans took their only lead with 28 seconds remaining when Matt Schaub threw an 11-yard TD pass to Andre Johnson.

The Texans got 185 of their 421 yards in the fourth quarter.

“First of all, it shows us that we’re not quite where we need to be,” linebacker Andy Studebaker said. “We played a good team the last two weeks and we’ve played them well. Had them both down to the wire. Yesterday, probably had that one in control. The feeling of having one escape from you makes you realize we’re not where we need to be yet.”

Johnson had a big day, catching eight passes for 138 yards against the Chiefs’ young secondary.

“I don’t know if there’s anyone better than him,” coach Todd Haley said. “He is a big-time receiver.”

Schaub was 25-of-33 for 305 yards and the Texans rushed for 132 yards, forcing the Chiefs to waste one of the best games their offense has played on the road in a while.

“They made a couple of great plays, we didn’t make a couple plays we could have made and then it became a shootout pretty quickly before guys understood what had occurred or what was happening,” Haley said. “And at that point then, it was too late.”