Safety Tyrann Mathieu has to sit on the sideline Wednesday as the Cardinals' rookies and assorted veterans went through a QB School workout.

In a move that doesn't come as any surprise, the Cardinals put safety Tyrann Mathieu and nose tackle Alameda Ta'amu on the physically-unable-to-perform list Wednesday as they ready to begin training camp.

Both players are coming off ACL injuries suffered late last season.

The move gives the Cardinals the option to keep them there when the regular season begins, which if it happened would mean the Cards would not have to count one or both against the 53-man roster until they were ready to play. But a player on PUP to start the season must also wait at least six weeks before playing, and at this point both Mathieu and Ta'amu are expected to be ready to at least practice before then.

Once a player practices, he must be removed from the PUP list and cannot return.

Both Mathieu and Ta'amu have been rehabbing faithfully this offseason at the team's Tempe complex. Both players returned this week and were working out Wednesday as some of the Cardinals took part in the team's "QB school" session.

Neither player has committed to any timetable of his return, although both have expressed optimism.

"I feel real good with my rehab," Ta'amu said Wednesday. "I think I'll be back sooner rather than later. I've been doing a lot of things on the field I couldn't do (a few weeks ago). I feel like my progression is coming along fast." 

In response to a fan's question on Twitter about when he planned on being back on the field full speed, Mathieu played coy. "It's a surprise," Mathieu tweeted. "Trying 2 avoid scouting report lol."

At the end of minicamp, coach Bruce Arians chose to be cautious in his own views of the return of the two key defensive pieces.

"That's strictly up to the doctors, trainers and them," Arians said in mid-June. "I'm not going to hurry them. We have plenty of time. If they aren't ready for the first day of training camp — which I doubt anyway, because I've never thought that -- I had Oct. 1, or after the (bye week) as the target date for me personally. If they do something better than that, God bless 'em."

The Cardinals also cut undrafted rookie wide receiver Kelsey Pope Wednesday.