Fright night for Jonathan Cooper, Cardinals

Rookie guard Jonathan Cooper's athleticism was on display Saturday night when the first-round draft choice pulled around the Arizona Cardinals' formation to deliver a block downfield with about 10 minutes remaining in the third quarter of an exhibition game against San Diego.

Unfortunately for Cooper, his quickness on this play would cost him. He was nine yards downfield and even with running back Alfonso Smith when Frank Beltre, an undrafted rookie free agent linebacker for the Chargers, tackled Smith and rolled onto Cooper's left foot.

Cooper's foot caught in the grass just long enough for it to roll inside-out in one quick, damaging movement. Cooper suffered a broken left leg, coach Bruce Arians told reporters after the game. He might miss the 2013 regular season, although Arians was not sure that would be the case.

The Cardinals drafted Cooper seventh overall to lead their offensive line for years to come. They had exceedingly high expectations for Cooper on draft day. They raised those expectations after seeing Cooper practice with the team. Now, they might have to wait a year before Cooper begins to make the desired impact. It's a brutal blow for Arizona.

"He has a unique skill set, maybe one of the more athletic offensive linemen I've [scouted] in the 15 years I've been in the business," Cardinals general manager Steve Keim said on draft day. "He has tremendous feet, bend, athleticism, space skills, and the ability to pull and play on the perimeter."

The Cardinals had neglected their line for years, at great cost to their quarterbacks, running backs and to the organization overall. Cooper was the first offensive lineman the team had drafted in the first three rounds since 2007, when Arizona selected Levi Brown fifth overall. Tennessee was the only other team to similarly neglect its line in the draft over that five-year span.

Arizona has a couple options with Cooper if the team determines he might be able to return this season. The team could leave Cooper on its active roster, or the team could place him on injured reserve with a designation for return. Teams can use the IR-DFR designation for one player each season. That player can return to practice six weeks after being placed on the IR-DFR list. The player is eligible to play in a game two weeks after that.

The Cardinals do have better depth on their line this season. Current right guard Daryn Colledge played left guard before Cooper's arrival. Bobby Massie, who played right tackle before the team signed Eric Winston, could project to guard. Paul Fanaika is another option.

But as the Cardinals prepared for a 2013 season within a rugged NFC West, they envisioned Cooper helping them meet the physical demands up front.

"Our division is so physical," Arians said on draft day, "and the thing that sets San Francisco, Seattle, and now St. Louis also, apart is their offensive and defensive lines of scrimmage are extremely good. We have to match that physicality on both sides of the ball."

That will be much tougher to do without Cooper. Arizona opens the regular season at St. Louis against a Rams team that tied for the NFL lead in sacks last season.

Cooper wasn't the only high-profile casualty for Arizona during its 24-7 defeat to the Chargers. Rob Housler, Dan Williams, Rashard Mendenhall, Andre Roberts, Matt Shaughnessy and D.C. Jefferson also suffered injuries of unknown severity.

This felt like a night with long-term negative repercussions for Arizona.