JACKSONVILLE, Fla. -- The Jacksonville Jaguars have changed offensive coordinators, but will that be enough to spark or fix a struggling offense?

Unless quarterback Blake Bortles starts to play better, the answer is probably no.

Bortles’ poor play isn’t the sole reason the Jaguars’ offense has stumbled around through the first seven games, but it’s certainly No. 1. His issue goes beyond his mechanics -- whether it’s a slightly longer windup, poor footwork and holding the ball too low -- and is instead much deeper.

He said after Thursday’s loss to Tennessee that he’s not sure why he’s playing poorly. He doesn’t know what’s causing that and he has no idea what to do to fix that. In addition, he’s said previously that he has been pressing and maybe even playing too tight.

That’s a quarterback whose mind is a mess, and that’s not something that can be fixed quickly. It’s a vicious cycle: He needs to devote time to get better, but he doesn’t have that kind of time because he has a game every week. As he continues to struggle, he gets more frustrated and presses more, which makes things even worse.

The problem is deeper than his mechanics as well. He's missing wide-open receivers, short-hopping the ball and can’t even make simple throws. Receivers have to reach behind or to the side or over their head to catch passes, and that disrupts the timing of the play.

So while Bortles is trying to fix his head, he’s also trying to be better fundamentally, which also is something that can’t be fixed quickly.

Add this into the mix: This will be Bortles’ third offensive coordinator in his three seasons. That’s less than ideal for a young quarterback.

He’s at least familiar with new offensive coordinator Nathaniel Hackett, who was hired as the quarterbacks coach in January 2015. I’ve been told that Bortles relates really well with Hackett and they spend a lot of time together. There will be no feeling-out process between the two and they will collaborate on what offensive adjustments they will make.

Hackett has had some success as an offensive coordinator in the NFL, too. He held that job in Buffalo in 2013-14 under head coach Doug Marrone, who is now the Jaguars’ offensive line coach/assistant head coach, and the Bills’ offense was one of the better ones in the AFC. They were tops in rushing (second in the NFL) in 2013, good in red zone efficiency, and the ball was spread around in the passing game. Three players had 60-plus catches in 2014 for the first time in Bills history.

It’s essentially what the Jaguars wanted to be this year: a team with a good run game that goes down the field with play-action passing.

There were legitimate reasons for Bradley to fire Greg Olson other than making him the scapegoat: The offense is on pace to set a franchise low in rushing yards and there have been instances of questionable playcalling. However, if Bortles doesn’t start playing better, it won’t matter because Bradley and the rest of the Jaguars’ staff likely will be joining Olson in the ranks of the unemployed.