INDIANAPOLIS -- Where has cornerback Quincy Wilson been?

That's been one of the Indianapolis Colts' biggest mysteries not involving Andrew Luck over the past five weeks. The Colts' second-round pick had a solid performance in Week 2 against the Arizona Cardinals (two tackles and two passes defended). He was then inactive for two weeks because of a knee injury.

The question has been, why has Wilson been a healthy inactive the past three games?

To make matters worse, it's not like the Colts are loaded with talent at cornerback. An argument could be made that Wilson has been their second-best cornerback behind Rashaan Melvin this season, but it's been players like Chris Milton, Kenny Moore II and Pierre Desire who have been active on game days.

Defensive coordinator Ted Monachino explained the situation Thursday.

"When Quincy practices and plays better than the other guys, he'll be up and he'll be playing," Monachino said. "He played in the Arizona game and he played very well. We're not at all worried about putting Quincy in the game. But he has to practice and prepare well. That's part of him being young and also part of him being a little immature and it's all a function of he's got guys that are pretty good pros that are working their tails off to keep him where he's at now. Hopefully that's a motivator for him. When he practices better and prepares better, he'll play more."

There's a chance that Wilson could be back starting at cornerback Sunday with veteran Vontae Davis against the Cincinnati Bengals. Melvin has yet to practice this week because he's been in the concussion protocol.

Of course, that could change if Wilson doesn't finish the week out with a solid practice.

"When we're out here at practice, he's got to know that every down counts," Monachinco said. "Playing in those windows when we're getting in very focused work in a certain area, he's got to understand that that's the area we're defending against. And if it's third down and medium, he's got play tight coverage.

"And if he can't, he can't be out there. So, it's not a matter of effort, and it's not even a matter of intelligence or want-to. He just has to show us on the practice field that he is dialed in and ready to go and mature enough to never take a down off mentally."