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JACKSONVILLE – David Caldwell got to the point quickly.

"We're going to be aggressive in trying to get this right and succeeding in getting this right," Caldwell said during his 2015 season-ending press conference at EverBank Field Tuesday.

"It's important we raise the level of expectations going into this offseason."

With that, a tone for the 2016 offseason was set:

Improvement must happen. That's particularly true of the defense, which the team late Tuesday afternoon announced no longer will be coordinated by Bob Babich.

Caldwell, the Jaguars' general manager since January 2013, said he absolutely believes defensive improvement is possible next season.

"We feel like it's easier in this league to fix a defense than it is an offense," Caldwell said. "It's not like we don't have any pieces on defense. We do have good players. We have a mountain of cap space and eight draft picks."

Caldwell cited nose tackle Roy Miller, defensive end Jared Odrick, middle linebacker Paul Posluszny, cornerback Aaron Colvin and cornerback Davon House and weak-side linebacker Telvin Smith as strong defensive players.

"We do have pieces in place there," Caldwell said. "Now, we have to supplement them. You get (Leo pass rusher) Dante Fowler (Jr.) back and (defensive tackle) Sen'Derrick Marks back, and we'll see where we're at."

Fowler missed the entire season with a torn anterior cruciate ligament and Marks missed all but four games with knee and triceps injuries. Caldwell didn't specify areas of need on the defense, but said the team – as it did last offseason – likely will again try to fill holes through free agency in March to allow as much flexibility as possible in the 2016 NFL Draft.

"It doesn't always work out that way, but I think this year will probably be the same plan," Caldwell said.

Caldwell said he didn't yet have an idea of how aggressive the Jaguars will be in free agency. The team signed eight unrestricted free agents last offseason: tight end Julius Thomas, Odrick, right tackle Jermey Parnell, safety Sergio Brown, wide receiver Bryan Walters, Otto linebacker Dan Skuta House and center Stefen Wisniewski.

The Jaguars are expected to be among the teams with the most salary-cap space when free agency begins, though Caldwell didn't provide a specific cap-space total on Tuesday.

"I don't know if we'll set the market, but we'll have our targets of guys that we really want and we'll do whatever we need to get them," he said.

Caldwell also added that while the Jaguars have focused on free agents between the ages of 25 and 29 the past two offseasons, he would consider slightly older players this offseason.

"We're at that point in time where we can compete and compete for championships," he said. "I have no issue with signing guys that are 30, 31 and 32."

With Babich no longer the coordinator, the makeup of the Jaguars' defense is uncertain entering the offseason. Caldwell said he expects the unit will continue to run a four-linemen, three-linebacker scheme, but said the Jaguars' personnel could adapt to a different defense.

"In looking at a lot of our key players, I think a lot of them – especially our young ones – could fit into any system," Caldwell said.

Also on Tuesday:

*Caldwell said quarterback Blake Bortles sustained a broken thumb on his left hand in the regular-season finale and will be in a cast "for a couple of weeks." He added of the media, "I don't want you guys to be alarmed about it."

*Caldwell said he remains confident third-year left tackle Luke Joeckel can be a "long-term answer" at the position. "I think he can be, I do," Caldwell said. "If you look at Weeks One through Sixteen he gave up two sacks. If the season ended Week Sixteen you probably wouldn't ask that question today." Joeckel allowed two sacks in the first 15 games before allowing five against Houston in the regular-season finale Sunday. Asked if Joeckel made progress this season, Caldwell said, "Yes, a lot of progress." …

*Caldwell said while Head Coach Gus Bradley's contract is scheduled to expire after the 2016 season, he is not worried about that influencing potential free agents. "The only worry is, 'Do you worry about distraction?''' he said. "Well, that's only a distraction if you let it be or if you guys [media] make it one." …

*Caldwell said the Jaguars would be open to the idea of coaching the Senior Bowl in Mobile, Alabama, on January 30. The Jaguars have coached the South team in the game the past two Januarys. "We will relish it and it's worked out well for us the first two years," he said. …

*Caldwell said if he could have done one thing differently this past season it might have been finding another solution to the pass rush when Fowler sustained a season-ending anterior cruciate ligament injury in rookie minicamp. Caldwell said the timing of the injury – in rookie minicamp in May – made finding adequate replacements difficult. "It's hard that time of year," he said. …

*Caldwell praised rookie guard A.J. Cann, saying the third-round selection "played as well as any offensive lineman I've been around. I don't think he gave up a sack all year." …

*Caldwell also discussed finding an elite-level free safety in this era of the NFL. "Finding a free safety is kind of like finding a franchise quarterback – if not maybe more difficult in my estimation," he said. …