KANSAS CITY, Mo. -- The goal for the Kansas City Chiefs on defense is to begin the season where the last one ended, not where it started.

Because the difference between the Chiefs' defense during the first 10 games last season and the final six was stark. It was 23rd in points allowed at almost 24 per game in the first 10 and led the league at 11.5 per game after that.

"We expect to pick up where we left off last season, as one of the best defenses in the National Football League," defensive back Tyrann Mathieu said. "It wasn't pretty, and I know we don't have this extra amount of first-round draft picks. We've just got a lot of guys that work hard and fit our scheme really well. A lot of those guys are coming back. The expectation is to be one of the best defenses in the National Football League and obviously to start the season faster and finish even stronger."

The slow start was not unexpected last year. The Chiefs had many new defensive components, including coordinator Steve Spagnuolo, a staff of assistant coaches, the base system and several players.

"At the beginning of the season we were trying to learn the defense," safety Juan Thornhill said. "We were trying to figure out how to play together, trying to figure out what were guys' strengths and weaknesses. Midway through the season we started to click because guys started to know.

"I didn't know what [Mathieu] was good at and I didn't know what he was bad at. Once we started playing a few weeks together we started to get that feeling that 'OK, I know he's going to do this.' We started making more plays because we were confident in what our teammates could do."

This year, the Chiefs have no convenient reasons for not starting better on defense. They're bringing back their full defensive coaching staff and 10 starters from Super Bowl LIV. They didn't have offseason practice or preseason games, but that's no different from any other team.

"With the challenges of what we're going through right now, we're all really glad it's not the first year," Spagnuolo said of the Covid-19 practice limitations. "It would be really hard. The guys that have been here and are in the same spots, that's been a tremendous advantage for us."

The veteran coach said the Chiefs still need more work before they would be where they were defensively at the end of last season. They won't have the benefit of preseason games to get there either.

"Just because you finish at a certain point at the end of one year does not mean you pick right up from that particular spot," Spagnuolo said. "We've got to go back to ground zero."

The Chiefs have had some challenges already. Frank Clark, Alex Okafor, Chris Jones and Damien Wilson have each missed practice time with illness or injury. Thornhill wasn't practicing at the start of training camp after last season's torn ACL. He has recently returned and is racing to be ready for the Sept. 10 opener against the Houston Texans.

The defense has had its moments in camp against one of the NFL's most potent offenses, though. In a four-play sequence in a recent practice against Patrick Mahomes and the starting offense, the defense deflected two passes, intercepting one. It also had a sack and forced a dropped pass with tight coverage.

Offense is coach Andy Reid's passion, but he doesn't mind seeing his defense stand up to Mahomes & Co.

"They're going back and forth," Reid said. "I love the fact they're challenging each other, which does nothing but make you better."

The defense can use that kind of work. Two of the Chiefs' first three games are against Deshaun Watson and the Texans and Lamar Jackson and the Baltimore Ravens. The Chiefs went 2-1 against those teams last season and eventually won a Super Bowl, but it wasn't enough. They want more.

"We could've been so much better, especially the production at the ball," Mathieu said. "I think I dropped eight interceptions by myself. Just understanding that if you make certain plays, it would've completely changed how well we played. I thought we played well, but it could've been great. So I think that's the motivation this year, that we know we can really get better.

"We're not necessarily patting ourselves on the back because we won a championship."