Detroit ended its official training camp Monday with a workout that looked more like a regular-season practice than the public training sessions held during the first part of the preseason.

The transition to a game preparation schedule didn't go smoothly, and coach Jim Schwartz voiced his displeasure at several points during drills.

“We didn’t do a good job keeping our focus on what we had to do,” Schwartz said. “We’re transitioning [during practice] from competitive periods to carded [scout team] periods, and [we were] sloppy.”

Schwartz will look for a more disciplined performance when the team returns from Tuesday's off day.

Nate Hughes is contending for spot at WR: Hughes' name wasn't part of the WR roster conversation until he caught three of the four thrown his way during Detroit's win over the Ravens Friday night. He continued that solid effort in Monday's workout by making several quality catches. Schwartz said the third-year player has inserted himself in the receiver competition. “[Hughes has] come on lately and had a lot of good practices,” Schwartz said. “He’s played well in his opportunities in preseason games. He’s a young player but he also has a little bit of experience in the NFL. You’re starting to see that [experience] from him.”

CB Justin Miller taking advantage of chances: Miller continues to make a strong case to earn a roster spot. The free agent signing is making the most of his return to football after sitting out last season to complete his college degree. His decision to suspend his career and finish school stemmed from a promise he made to his grandmother, who passed away in 2010. Miller began training camp with the third-team unit, but his five years of NFL experience -- including stints with the Jets and Raiders -- have paid dividends as his reps increase. If Miller maintains his current level of play, he could very well pass rookie Jonte Green in the race to win the Lions' final CB roster place.

WR Titus Young misses workout: A week after missing three days -- and the Lions' preseason opener -- to attend the birth of his son, WR Titus Young was again absent from Monday's practice. He caught a 24-yard touchdown pass against the Ravens Friday that proved to be his only catch of the game, and then missed Sunday's practice with what Schwartz described as “soreness.” Schwartz didn't comment on the circumstances behind Young's absence Monday except to say that he was excused for noninjury reasons. That answer wouldn't normally be cause for concern -- especially for a player with a newborn child -- except for the fact that Young's offseason was marred by a week-long absence from OTAs following an incident with teammate Louis Delmas. It'll be interesting to see whether Young is present at Wednesday's workout. If he's not, he'll surely face questions about the missed practices when he returns.

Lions waive two injured players: Detroit waived/injured TE Nathan Overbay and S Don Carey on Monday. The waived/injured list is a preseason version of injured reserve. Both Overbay and Carey will revert to the Lions' injured player lists if they clear waivers, but they will no longer count against the 90-player roster limit. No corresponding roster additions have been announced, so it's unclear whether Detroit will add more players, or use Overbay and Carey as two of the ten cuts the Lions must make by Aug. 28.

Follow Lions reporter John Kreger on Twitter at @CBSSportsNFLDET and @johnkreger.