ALLEN PARK, Mich. -- The Detroit Lions' minicamp might be mandatory, but apparently not for everyone.

Two players missed the first day of the last offseason workout before training camp. One, rookie receiver T.J. Jones, had been around for everything else and had an excused absence. The other, cornerback Chris Houston, has not been around at all.

Houston, who is coming off toe surgery this spring, has not been around at all during the OTA period or now during minicamp. Apparently, head coach Jim Caldwell isn’t expecting him here, though every other injured player who isn’t participating is still here -- including defensive end Ezekiel Ansah and running back Joique Bell.

Neither has practiced this spring, either, but they have been around to learn the new offense and defense mentally. Houston has not. So how does he keep up with the rest of his teammates?

“I would think that was sort of a trick question. He hasn’t been here,” Caldwell said. “How does he keep up? He hasn’t been here. We understand he hasn’t been here. He’s been excused.

“When he gets back or whatever happens, we’ll work it out at that time.”

It is unlikely that "whatever happens" would be a release. Houston is due $4.8 million against the salary cap this fall and would be owed a total of $5.2 million in dead money. That makes it cost prohibitive to cut the 29-year-old, who signed a five-year deal before the 2013 season.

With Houston not even on the premises, let alone at practice, the Lions have started Darius Slay and Rashean Mathis at cornerback with Bill Bentley in the slot. Those have been the two top cornerbacks for Detroit during spring workouts.

This is after Houston struggled with injuries -- and therefore, consistency -- throughout last season. He was a starter for the Lions, but was benched against Cincinnati after being routinely beaten by double moves from Bengals receiver A.J. Green.

Houston had a career-low 44 tackles last season and only two interceptions. The 12 games he played in also tied a career-low, matched in 2009 with Atlanta.

And now, he hasn’t been around -- even if Caldwell didn’t expect him to be.

"We excused him. He is not expected to be here," Caldwell said. "He is right where he’s supposed to be at this point in time. It is where we expect him to be."

Where that is is unclear except for one thing: Right now, Chris Houston is not expected to be in Detroit with the rest of the Lions.