INDIANAPOLIS — As the saying goes: when it rains, it pours.

For the Indianapolis Colts' secondary, it's officially hurricane season.

Already missing No. 1 cornerback Vontae Davis and starting free safety Clayton Geathers — and several key backups — going into Sunday's 2016 season opener against the Detroit Lions, the Colts saw two additional key members of the secondary, Patrick Robinson and T.J. Green, leave the game with injuries.

While the immediate status of Robinson, who suffered a concussion, and Green, who suffered a sprained knee, is unknown, the Indianapolis defense had to lean on three brand new members of the team — as in, signed in the week leading up to Sunday's game — to try to stop Lions quarterback Matthew Stafford & Co.

Stafford certainly took advantage of the Colts' injury woes, dinking and dunking his way up and down the field all day to the tune of 31-of-39 completed passes for 340 yards and three touchdowns in the Lions' 39-35 victory at Lucas Oil Stadium.

"It's hard, you know? Injuries play a big role in that," Colts safety Mike Adams said of all the moving parts and the final result on Sunday. "That's something you can't control."

For safety Matthias Farley and cornerbacks Rashaan Melvin and Darryl Morris, Sunday's game was the culmination of a whirlwind few days.

Farley was signed Sept. 4, giving him a full week to come in and learn the Colts' system the best he could to be prepared for Sunday's season opener. Morris (signed Sept. 5) and Melvin (signed Sept. 7), meanwhile, had even less time to get their bearings before they were thrown into the fire against the Lions.

For the most part, the new trio didn't miss assignments or allow any huge plays over the top. But the defense as a whole struggled to take Detroit ballcarriers to the turf throughout the entire game, especially when they had even a little space out in front of them to break free.

"I can't speak for everybody, but I think I missed a couple (tackles), and that's just not knowing where my help is," said Morris, a fourth-year veteran with previous experience in San Francisco (2013) and Houston (2014-15). "It's just getting on the same page. And then it comes down to just breaking down and tackling your man and getting him down on the ground. You've just got to play football."

Adams spoke to the communication issues after the game, as he was constantly seen directing traffic — even more than he usually does throughout a typical contest.

Also factoring in to the equation was veteran cornerback Antonio Cromartie, who was signed by the Colts on Aug. 22 but did not play in any preseason games after going unsigned the entire offseason.

Cromartie played the entire game Sunday.

"They're in there because we trust them," said Adams, who had eight tackles Sunday. "The only thing I can say is that I didn't have enough time to work with them per-say. It is what it is, they have to step up. It's not their fault. I think they did a good job when they went in there, but injuries played a key in that."

For Melvin, the week leading up to the game was nothing new. He's bounced around a few rosters since entering the league in 2013, and knows that you just have to be ready when your number is called.

"When you come in, you come in because you understand that you're there for a reason," he said. "You get a couple of days to learn the playbook and you learn those plays, and you've got to go out and compete like everybody else is competing and help the team win."

By next Sunday, when the Colts travel to take on the Denver Broncos, the Indianapolis secondary could see the return of guys like Davis, Geathers and injured cornerback Darius Butler, as well as Robinson and Green.

But guys like Farley, Melvin and Morris are going into the new week ready to improve upon their performance against the Lions. If needed, they'll throw on the pads and compete again.

"You come into the game thinking that you're going to play," he said. "You come in with that mentality, then you will be ready for that mentality, and I think we both showed — Darryl Morris and I both showed — that we can come in and play."