JACKSONVILLE – Head Coach Gus Bradley spent much of Monday morning focused on the Jaguars' defense. What he saw was far from ideal.

"Overall, we just should be playing better defensively," Bradley said.

Bradley's words came Monday at his weekly next-day news conference, a day after he named rookie Blake Bortles the team's permanent starting quarterback in the wake of a 44-17 loss to the Indianapolis Colts in Sunday's regular-season home opener.

The Jaguars produced 55 yards offense in the first half against the Colts, but performed better statistically in the second, producing 289 total yards and 17 points as Bortles completed 14 of 24 passes for 223 yards and two touchdowns with two interceptions.

The defense improved statistically, too, holding the Colts to 199 yards and seven points in the second half after allowing 321 yards and 30 points in the first. But Bradley said there are enough concerns there that changes could be made before Sunday's game against the Chargers in San Diego.

"We're going to take a look at it and there may be a change," Bradley said.

The Jaguars allowed the Colts 529 yards offense Sunday and are ranked 32nd in the NFL in total defense. They struggled with missed tackles in a Week 2 loss to Washington, and Bradley said while he didn't think there were as many missed tackles Sunday, the area remained an issue.

"We did miss quite a few tackles, especially in the first half," Bradley said.

Bradley said the defensive front for the most part played well Sunday, and he has praised the play of tackles Sen'Derrick Marks and Roy Miller and defensive end Andre Branch much of the season. He also said Monday that safety Johnathan Cyprien and middle linebacker Paul Posluszny are playing well, and that defensive end Red Bryant played well Sunday.

"There are some guys that are playing well," he said, adding of the back seven, "Behind them is where we need to take a look at some things."

Bradley said Monday there is a chance of lineup changes defensively, and said the cornerbacks aren't competing for the ball as they should.

"I don't see us challenging routes like we need to," he said. "We need to take care of that."

Bradley also addressed linebacker, particularly the Otto position where LaRoy Reynolds and Dakoda Watson have shared time the last two weeks with Watson backing up Reynolds.

"We had some challenges going on there," Bradley said. "We missed some tackles. We had some opportunities to make plays and we didn't capture those opportunities."

While Bradley was asked after Sunday's game about possibly taking over defensive play-calling, he said Monday the issue wasn't as much calls as execution.

"It's more the responsibilities within the calls," he said. "When I look at that, I see 10 guys doing it right and one guy not doing it right."

Bradley also said sometimes players are trying to do too much, and that sometimes technique errors have been a concern.

"Even some of our better players, I think we need to tighten up on that," he said. "It's leaning down to where it's a trust issue. 'Do I trust that you're going to be where you need to be? Am I going to trust that you understand your responsibilities?' A little bit of that I think is an issue.

"There were some just blown assignments, things I don't know where they came from. Those things seem to come up repeatedly with some guys. We need to find what exactly went wrong."

Also around the Jaguars Monday:

*Safety Chris Prosinski sustained an elbow/triceps strain and will miss between two-to-four weeks, the team announced. …

*Wide receiver Marqise Lee (hamstring), who missed the loss to Indianapolis, will be evaluated throughout the week. He is not expected to play against San Diego Sunday. …

*Middle linebacker Paul Posluszny sustained an ankle injury against Indianapolis and will be evaluated Wednesday. …

*Tight end Clay Harbor (calf) should practice Wednesday. He returned to practice last week after being out since early training camp, but was inactive Sunday.

*Offensive tackle Austin Pasztor (hand) will continue to be evaluated this week. He has been out with a hand injury since Week 2 of the preseason. He worked full last week in practice with a protective club on his hand, but was inactive Sunday.

*Fullback Will Ta'ufo'ou sustained an ankle injury against Indianapolis and will be evaluated during the week. …

*Running back Toby Gerhart played through a foot injury Sunday and sustained no setbacks. …

*Bradley said running back Denard Robinson could continue to have an expanded role. Bradley said the second-year veteran has earned more reps in recent weeks, and that could continue. Robinson rushed for 33 yards on eight carries Sunday, with Gerhart running for 32 yards on nine carries. …

*Bradley said the offense played poorly in the first half Sunday, and that the energy level and execution improved when Bortles entered the game in the second half. The offense went three-and-out or less on four of six drives in the first half and no such drives in the second. "That doesn't generate a lot, and at times that can affect the defense," Bradley said. …

*Bradley later in the press conference said while offensive struggles can hurt a defense that he can't allow himself or the defense to think that way. Asked if the offensive struggles were a reason for the defense's struggles, Bradley answered simply. "No," he said. …