JACKSONVILLE – The primarily storyline remains quarterback.

That will be true for the Jaguars in both halves of their preseason game against the Chicago Bears at Soldier Field in Chicago, Illinois Thursday night. That's true even though the interest of many fans and observers may focus mainly on the final two quarters.

The reason for the second-half interest:

That's when rookie quarterback Blake Bortles will play.

Chad Henne, the Jaguars' starting quarterback, will start and play the first half, Jaguars Head Coach Gus Bradley said this week, with Bortles – the No. 3 overall selection in the 2014 NFL Draft from the University of Central Florida – expected to play the entire second half.

That's it. That's the Jaguars' quarterbacking breakdown – Henne starting, Bortles backing up – and that's how it stands for the foreseeable future.

And while many have spent the last 10 days focused on the rapidly improving Bortles – and while Bortles' development remains the primary long-term story around the franchise – for the short-term it's important that Henne and the first-team offense develop a rhythm.

That will be the focus early Thursday.

Henne, who team officials have said will start the regular-season opener and beyond, completed four of seven passes for 40 yards in the first quarter of a 16-10 preseason-opening victory over Tampa Bay. The Jaguars' wide receivers missed multiple assignments during that period, and center Mike Brewster twice had errant snaps that led to significant losses.

The Jaguars want to see the first-team offense more efficient, and though Henne appears in no danger of not starting the regular season, he will be a huge focus on Thursday.

Other storylines to watch Friday:

1. Bortles, Bortles, Bortles.The reality is as many or more eyes will be on the Jaguars' offense in the second half Thursday than in the first. That's because the progress of Bortles is not only key to the franchise's long-term future, it has excited the fan base in the short-term to a remarkable level. Not only did Bortles look very good in the team's scrimmage a week and a half ago, he looked even better against Tampa Bay Friday. Bradley and offensive coordinator Jedd Fisch noted several times this week that Bortles in fact played a Tampa Bay defense that blitzed only once and was pretty vanilla overall. That means Bortles has significant developments remaining when teams show more exotic blitzes and when they begin designing defenses to combat his strengths. Those are two reasons the Jaguars aren't tripping over themselves to anoint Bortles the Franchise Guy right now. Still, while Bortles has developing to do, he was good enough last week to merit the intense interest that is coming and will continue to come his way.

2. Center of attention.If you've followed this team at all through training camp, you know the story: Brewster entered training camp as the starter, and while he will start a second consecutive preseason game Thursday, Jacques McClendon, rookie Brandon Linder and rookie Luke Bowanko are all expected to work at the position, with Brewster, McClendon and Linder now competing as a trio for the starting right guard/center positions. Brewster is still very much the starter, but this area likely will remain very much a storyline throughout training camp.

3. Run to win.The Jaguars entered the preseason opener wanting to work on the run. That was important enough that Fisch said this week he wasn't as much concerned with how effective the team ran against the Buccaneers as he was with getting a young, relatively inexperienced offensive line significant repetitions run-blocking together. The group of Austin Pasztor, McClendon, Brewster, Zane Beadles and Luke Joeckel struggled enough early against Tampa Bay that they requested an extra series. Starting running back Toby Gerhart will make his Jaguars debut Thursday. That should give the running game a boost, but the quest for consistency from this area likely will be a focus for the next several weeks and perhaps months.

4. Sorting out the depth.This is happening all over the roster, but it's happening in a big way at running back. Gerhart is clearly the starter, and while the team considers him the "workload" back he's not expected to rush more than about 15 times a game. That means running back will very much be "by committee," and Fisch said this week a focus for the remainder of the preseason will be determining the size of that committee. Jordan Todman has worked with the second-team throughout much of camp, and rookie Storm Johnson worked ahead of second-year veteran Denard Robinson last week. All three reserves – Johnson, Todman and Robinson – have impressed coaches.  All four backs seem to have a real chance to make the roster, but what roles Todman, Johnson and Robinson play is still very much shaking out.

5. Maintain momentum.This is true of the entire team, which got a lift from a solid performance in the preseason opener. But it's particularly true of the defense. The front was dominant against the run against Tampa Bay, and an aggressive start helped put the Jaguars' pass rush in position for three sacks, nine pressures and two forced fumbles. Jaguars safety Winston Guy also returned an interception for a touchdown. The Bears are a significantly better offense than Tampa Bay, with running back Matt Forte, quarterback Jay Cutler and one of the NFL's top receiving tandems, Alshon Jeffery and Brandon Marshall. Middle linebacker Paul Posluszny won't play because of a biceps contusion, but overall the defensive front will get a more significant test than in the preseason opener.