The Kansas City Chiefs are not only searching for how to contain the run. They must also hope that quarterback Patrick Mahomes cannot be contained to the pocket.Those conclusions were apparent in the Chiefs’ first loss of the season, and both aspects remain concerns as Kansas City (4-1) prepares for a Sunday matchup against the Houston Texans (3-2) in Kansas City, Mo.”It’s no mystery what teams are coming in here to do,” Chiefs defensive end Frank Clark said. “They are seeing 150 yards (allowed rushing). When you see things like that, it excites you as an offense.”That’s especially true when Kansas City’s inability to blunt opposing rushers keeps Mahomes from executing as many plays. As it is, the mobility of the NFL’s reigning MVP has been limited by a tender left ankle he aggravated Sunday in a 19-13 prime-time loss to Indianapolis.The Chiefs’ average yield of 155.8 rushing yards ranks 30th in the NFL, and their yards per carry permitted (5.30) ranks 31st. Opponents have rushed for 203, 186 and 180 yards in the last three games. And now the defense is without its top playmaker, tackle Chris Jones (groin) for at least a week. Another starting lineman, Xavier Williams (ankle), is also out, having landed on injured reserve. The team signed Terrell McClain this week for depth.Expect the Texans to exploit the vulnerable Kansas City run defense. They rank 10th with a 129.4-yard rushing average and ninth with a 5.05 per-carry average behind a pair of offseason acquisitions, Carlos Hyde and Duke Johnson.”They run hard, they’re smart, they know what we’re trying to do with them,” Houston coach Bill O’Brien said. “They try to go out there on Sundays and execute as best as they can, being fairly new in the system. They’ve both helped us quite a bit.”Protection for quarterback Deshaun Watson is spotty considering the Texans have allowed 18 sacks, though Houston kept Watson entirely clean on Sunday, and the Chiefs’ battered defensive front could have trouble applying conventional pressure.Mahomes, meanwhile, was sacked more times (four) in the loss to Indianapolis than he had been in the previous four games (three). If his mobility remains limited, Mahomes’ capabilities diminish, especially with his top wide receivers, Tyreek Hill (collarbone) and Sammy Watkins (hamstring) ailing.