Chris Houston sat out because of a migraine and Louis Delmas is still nursing a balky knee.
The Detroit Lions hope their secondary will be much improved this season — but first, they need their top players healthy and on the field together.
"You'd like to have continuity," coach Jim Schwartz said. "That can be an issue at times."
Houston and Delmas both missed practice Monday, and although there were plenty of other defensive backs eager to take their place, the Lions are well aware that it's important for cornerbacks and safeties to develop chemistry before the season starts. That's not easy when key players are sidelined.
Detroit re-signed Houston, a cornerback, and Delmas, a safety, in the offseason. The Lions also signed free agent safety Glover Quin and drafted cornerback Darius Slay in the second round. Some stability would be welcome after Houston was the only Detroit defensive back to start more than nine games last season.
"If we have a healthy secondary, I think we can be the best secondary in the NFL," Slay said.
The Lions don't need to have the best secondary in the NFL. If this group can be solid behind a defensive front that includes Ndamukong Suh and Nick Fairley, Detroit's defense could be stout.
Houston has been productive, starting 42 games over the last three years. Delmas has also been a mainstay, but he was limited by left knee problems and played only eight games last season. Delmas didn't play in Detroit's exhibition opener Friday against the New York Jets.
Houston says his migraine problems are hereditary and have bothered him since he was young, although they don't seem to have affected his career much. He's hoping the Detroit secondary can become the type of cohesive unit that can help the Lions grow into an elite team.
"In Seattle, those guys have got chemistry together. They've been playing together for two, three, four years. Same thing in San Francisco," Houston said. "You trust each other on the field, you know how each other plays, and you hold each other accountable. It's like a brotherhood."
The Lions beat the Jets 26-17, but when Schwartz reviewed the game, he found a few areas that needed improving for the secondary.
Detroit defensive lineman Ziggy Ansah intercepted a screen pass and returned it for a touchdown, but aside from that, Jets quarterbacks Mark Sanchez and Geno Smith looked fairly comfortable, going a combined 16 of 20 for 172 yards and a touchdown.
"When you get done with the game, you're happy because you won the game. The old saying is, it's never as good as you think it was and it's never as bad as you think it was," Schwartz said. "I think this was definitely one of those cases where it wasn't as good as we thought it was. Couple of plays that you saw we had bad leverage and missed some tackles in the secondary. That's critical. You can't do that. We had a couple plays on third down where they made plays into the strength of our defense. We didn't play physical enough at our corner position when it came to man-to-man coverage."
It's hard to read too much into the first exhibition game, since starters don't play a lot, but for the Lions, secondary depth is crucial. Cornerback Bill Bentley, a third-round pick in 2012, started three games as a rookie. Safety Don Carey started six games last season, and he could be an important player for Detroit if Delmas isn't at full strength.
"It's life in the NFL," Schwartz said. "There's always going to be times when you're not able to get them all on the field at the same time."