Change to Patrick Mahomes at QB the major story at Chiefs camp

Patrick Mahomes takes over for Alex Smith at quarterback, and if he can succeed, the Chiefs' offense could be one of the NFL's best. AP Photo/Charlie Riedel

The Kansas City Chiefs open training camp on July 26 at Missouri Western State University in St. Joseph. Here's a closer look at the Chiefs' camp:

Top storyline: The Chiefs are making their first change at quarterback since 2013, when they traded for Alex Smith. His replacement, Patrick Mahomes, isn't just any QB but the first drafted by the Chiefs in the first round since 1983. But the Chiefs aren't viewing this as a developmental season for Mahomes, who played in just one game last year as a rookie. They're expecting him to play well and for the offense -- which includes top veteran skill players in tight end Travis Kelce and wide receivers Tyreek Hill and Sammy Watkins -- to score a lot of points.

QB depth chart: The Chiefs are fully committed to Mahomes as the starter. Veteran Chad Henne, signed over the winter as a free agent, is solid as the top reserve. The only real depth-chart intrigue at this position is over the final roster spot, where another veteran free-agent addition in Matt McGloin battles undrafted rookie Chase Litton. Expect McGloin to win that battle but Litton to stick around on the practice squad.

Bubble watch: Unless injuries do the work for them, the Chiefs face their most interesting roster decisions at running back. Starter Kareem Hunt led the NFL in rushing last season as a rookie, but the Chiefs have four others who have been productive NFL backs at one time or another. Charcandrick West led the Chiefs in rushing in 2015, but he faces a challenge for a roster spot from two free-agent additions, Damien Williams and Kerwynn Williams. The Chiefs like West as a pass receiver and blocker and special-teams player, so he could be difficult to unseat.

This rookie could start: Third-round linebacker Dorian O'Daniel won't play in the regular defense but should see a lot of work on obvious passing downs and special teams. O'Daniel is only 220 pounds, so the Chiefs don't view him as a run defender. But he showed the speed, coverage skills and knowledge of the defensive schemes during offseason practice that he'll compete for a regular job in passing situations.

Establishing a defensive identity: The Chiefs over the offseason put an emphasis on getting tougher defensively, particularly against the run. They signed a nose tackle in Xavier Williams, an inside linebacker in Anthony Hitchens and drafted defensive players with their top five choices. They can't afford to wait long for their efforts to pay off. The Chiefs struggled on defense most of last season and allowed three long touchdown drives in the second half of last season's playoff loss to the Titans. The Chiefs also need more from their pass rush. One of their top edge rushers, Dee Ford, returns after missing most of last season with an injury.

Who's where on the offensive line? The Chiefs finished offseason practice unsettled at two starting line spots. Center Mitch Morse was unable to practice while rehabbing a foot injury, and the Chiefs were searching for a starter at left guard. The Chiefs need a quick return from Morse at camp and to resolve the left guard issue as soon as possible. If their line isn't functioning well when the regular season begins, the Chiefs will have a difficult time achieving their offensive potential.