Eight in the Box: NFC West camp battles

One key positional battle for each NFC West team as training camps get underway.

Arizona Cardinals: Rashard Mendenhall and Ryan Williams are fighting for the starting job at halfback. Both have had injury problems recently. Mendenhall is the more proven option. He also played under new Cardinals coach Bruce Arians when they were with the Pittsburgh Steelers from 2008 through 2011. Mendenhall averaged 1,103 yards and 9.7 touchdowns per season in that span, by far the most productive stint of his career. As Arians put it back in March, "Rashard is a proven back who can carry a team to a Super Bowl. We’ve got a good history together and know how to use him. But he is a heckuva player in all phases. He never has to come out of the game. The depth that it puts in our backfield is really exciting."

St. Louis Rams: Daryl Richardson, Isaiah Pead and rookie Zac Stacy are the leading candidates to start at halfback now that Steven Jackson has moved on. The team probably will take a committee approach to the position. Richardson outplayed Pead when both were rookies last season. Pead, a second-round choice, was playing catch-up as a rookie after rules prevented him from practicing with the Rams until June 7. Pead faces another challenge this season after the NFL suspended him for the first game of the season, citing a violation of the substance abuse policy. The Rams expect big things from Pead, but this is looking as if it could be a pass-oriented offense without a workhorse running back. Stacy comes closer than the others to fitting the power profile. He has a chance to emerge as a primary runner on early downs.

San Francisco 49ers: The 49ers do not yet know which receiver will start opposite Anquan Boldin while Michael Crabtree recovers from surgery to repair a torn Achilles tendon. Crabtree is expected to miss most or all of the 2013 season. Kyle Williams worked opposite Boldin in the first camp practice. A.J. Jenkins caught zero passes as a 2012 first-round pick, but he could be a leading candidate, as well. The team is also hoping to develop rookie fourth-round pick Quinton Patton and somewhat enigmatic Ricardo Lockette, who has been living with quarterback Colin Kaepernick. Lockette earned high, unsolicited praise from coach Jim Harbaugh earlier in the offseason. The 27-year-old is 6-foot-2 and weighs 217 pounds, giving him prototypical size. He also ran the 40-yard dash in under 4.4 seconds at the combine. Lockette played in two games with Seattle in the 2011 season, catching two passes for 105 yards and a touchdown in the final two games of that season. He hasn't played in a regular-season game since. Don't forget about Mario Manningham. He's not yet healthy, but the 49ers have him for the season.

Seattle Seahawks: It's not yet clear how the Seahawks will divide playing time at wide receiver. Percy Harvin is obviously going to be an every-down player if his recently disclosed hip injury isn't serious. Golden Tate and Sidney Rice also will play extensively, but one of them could see his snaps diminish in base situations. Doug Baldwin probably also will command playing time. Harvin's injury situation is a pivotal variable. Coach Pete Carroll said he's not particularly worried because so much time remains before the regular season. Although some thought Tate's playing time would suffer when the team acquired Harvin, the Seahawks thought the move would create even better matchups for Tate, who caught 45 passes for 668 yards and seven touchdowns last season. This is a contract year for Tate. Something or someone would have to give -- Rice, most likely -- if Tate earned a significant contract extension for Seattle. This is a highly competitive situation.