INDIANAPOLIS — D'Qwell Jackson stood at his locker Sunday night, finally ready to answer reporters' questions after his Indianapolis Colts defense had allowed the Detroit Lions to move 50 yards in just 37 seconds to kick a 43-yard field goal and defeat the Colts, 39-35, at Lucas Oil Stadium.

Jackson knew what was coming: how can this happen? How can the Colts' defense, already decimated due to injuries — particularly in the secondary — have such a lackluster performance that included missed tackle after missed tackle, and the one time the team needed a stop with the Lions' backs up against the wall, they couldn't deliver?

"We didn't play good enough," the veteran inside linebacker said, matter-of-factly. "It started with me. We've got to play better towards the end. Any time you give up that many points, in this league, you're blown out. And we can't put our offense — we can't put this team — in that position."

Both the Colts' defense and their offense got off to slow starts on Sunday, as Indianapolis found itself down 21-3 late in the second quarter before quarterback Andrew Luck started to get into a groove. His three-yard touchdown pass to Donte Moncrief at the end of the first half made the deficit a little more bearable at 21-10 going into halftime.

But Matthew Stafford and the Lions' offense kept dumping off short passes in the second half — and the Colts' defense kept missing tackles. What should've been short gains, or even losses, for Detroit turned into huge chunks of yards over and over again, as the Lions continued to have their way on that side of the ball.

In the end, the Colts had allowed 448 net yards, including 332 through the air to Stafford, who completed almost 80 percent of his 39 passes on the night and had three touchdowns.

This definitely wasn't the start the Colts' defensive players or coaches envisioned when they began the offseason workout program, or even when they began preparations for Sunday's game.

"To start the season off, I'm pissed, because that's not a result of our hard work that we put in all spring," Jackson said. "It's not who we are … I'm pissed off right now because we worked too hard — coaches do as well — putting the plan together; we got plenty of time to prepare for these guys. It's not like they surprised us."

What's even more frustrating for Jackson is the fact that Luck and the Colts' offense never really stopped their momentum for the rest of the game. Indianapolis racked up 450 total net yards on the night, as Luck completed 31-of-47 passes for 385 yards and four touchdowns to no interceptions.

The Colts' defense, Jackson said, simply didn't hold up its end of the bargain on Sunday.

The team will review the film on Monday, when it begins preparations for next Sunday's opponent — the reigning Super Bowl champion Denver Broncos. And if Jackson has his way, there will be no need to be as upset as he was after the Lions game for the rest of the season.

"Defensively, that's not going to be us moving forward," he said. "We cannot give up that many points on any given night. The offense had a terrific day moving the ball, scoring, not turning the ball over. That's not us. That's not who we are, that's not what we're going to stand for this year. We have to play better; we will play better."