Just in time for the start of voluntary practices, someone turned the furnaces up. It’s supposed to be around 108 on Tuesday when the Cardinals hold their first voluntary full-squad workout.

Coach Ken Whisenhunt, however, is smart about handling these practices. They are scheduled for 90 minutes, and part of that time includes stretching, etc. He’s not trying to replicate Bear Bryant’s Junction City, Texas camp.

Here are five of the areas I’m especially interested to watch over the next month as the Cardinals hold their organized team activities (OTAs) and minicamp.

Quarterbacks — This is the big one, obviously. There is competition between Kevin Kolb and John Skelton for the starting job. Rich Bartel and rookie Ryan Lindley could be competing for a roster spot. Position meetings can sometimes be like an old one-room schoolhouse. One student, say a 10-year veteran, is ready for calculus. Another, say a rookie, is learning multiplication tables. That’s not the case with this group. The Cardinals four quarterbacks aren’t exactly at the same level, but it’s close. There is no 10-year veteran in the room who has been there, done that.

Running backs — On the surface, it appears to be a postion of strength. But we thought that last year, and injuries changed the perception. Starter Beanie Wells hinted pretty strongly to Darren Urban of azcardinals.com last week that he probably won’t participate fully in off-season work as he recovers from knee surgery. Backup Ryan Williams is rehabbing from a torn knee tendon, and his target for return is training camp. That leaves LaRod Stephens-Howling, Alfonso Smith, William Powell, and Javarris James to handle the work load.

Right offensive tackle — Players won’t be in pads, but it will still be intriguing to watch rookie Bobby Massie, the fourth-round pick. He looks the part of a starter, but he’ll be challenged by Jeremy Bridges and D’Anthony Batiste. I’m curious, too, about rookie left tackle Nate Potter, not so much to see if he can contribute this season, but to get a hint of his future.

Nose tackle — I doubt if Dan Williams will be 100 percent for the start of OTAs. His rehab from a broken arm is progressing normally. But it was a severe break, and it took a while for Williams to rebuild strength. But he’s been around the facility all off-season and apparently has kept his weight down.

Cornerback — Lots of competition for the job opposite Patrick Peterson. William Gay, Greg Toler, Jamell Fleming, A.J. Jefferson. This will be a fun position to watch throughout the summer.

NOTE: OTAs are closed to the public. The only practice open to fans before camp in Flagstaff is June 13 at University of Phoenix Stadium. It will be an evening workout and no other details have been set.

The Cardinals signed offensive tackle Nate Potter, their seventh-round pick, to a four-year contract, the team announced on Thursday.

Financial terms were not released.

Potter is the fifth of seven draft picks to sign. The team’s top two selections, receiver Michael Floyd (first round) and cornerback Jamell Fleming (third round) have not signed.

Potter started 42 games in four seasons at Boise State and played in 51 of a possible 53.

The Cardinals reached the roster maximum of 90 players Wednesday when the team signed free agent defensive end Landon Cohen.

Cohen, 6-feet-3, 300 pounds, has played in 25 NFL games, starting five of them. He played in one game with New England last season.

The Lions drafted him in the seventh round out of Ohio in 2008. He spent two seasons with the Lions and has also been with Jacksonville.

The Cardinals had one spot open on the roster and obviously needed some depth at defensive end. Signing Cohen doesn’t preclude them from reaching agreement with defensive end Vonnie Holliday or outside linebacker Clark Haggans. Whenever that happens, the club will make a corresponding roster move.

Holliday and Haggans aren’t the type of guys who need a lot of work in the off-season to get ready. No one in the NFL keeps himself in better shape than Haggans. But I don’t think the Cardinals will wait too long to bring them in. Both are good guys who could serve as mentors to the many young players on the team.