It’s tough to remember a time when cornerback was not a weakness or an issue for the Lions.

Perhaps the page has finally been turned.

“Healthy, this is the best group of corners we’ve had,’’ coach Jim Schwartz said on Monday. “We still have a long way to go. They have to prove it over a period of time. We have seen some good flashes from some young players like (Darius) Slay and Bill Bentley, but the proof is going to be over the course of time.”

After four days of training camp, the Lions have three cornerbacks out with injuries (Ron Bartell, Jonte Green, Chris Greenwood) — not considered serious at this point. There is some depth at the position.

Last year as a rookie Bill Bentley won a starting job out of camp. Then a shoulder injury held him to just four games. He was shut down for the rest of the season. He’s come back flying and could be the starting nickel when the season starts.

When camp started Chris Houston and Bartell lined up with the first team. Bartell, a veteran, had a solid spring in OTAs and minicamp.

Darius Slay was drafted in the third round in April to beef up the position. With the three injured corners, he’s been getting more reps and seems to be making the most of them.

“Chris (Houston) has had an outstanding camp so far. He’s done really well,’’ Schwartz said.

Domonique Johnson, DeQuan Menzie and Ross Weaver are also in the mix.

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