JACKSONVILLE – A lot went right for the Jaguars in Preseason Week 1.

And make no mistake: the Jaguars will want a lot of that to go right again in the second game of the preseason Saturday against the New York Giants – perhaps most notably, the play of quarterback Blake Bortles and the offensive line.

But what about the things we didn't see in Week 1?

What about what's new? The changes?

Defensive end. Defensive tackle. Safety. Tight end. Maybe running back. All will have a different look for the Jaguars in Preseason Week 2 compared to Preseason Week 1. As such, all are storylines as the preseason approaches its midway point.

One huge change could be at running back, so we'll discuss that first. T.J. Yeldon, the No. 36 overall selection in the 2015 NFL Draft from Alabama, has not been ruled out. That means he has a chance to make his NFL preseason debut Saturday at MetLife Stadium.

If that's the case, we could see the future of the Jaguars' running back position. Yeldon has worked in a red, non-contact jersey much of the past two weeks, but before that – in training camp and the offseason – he showed signs of being special.

Even if he plays, he won't start. The starter Saturday likely will be Denard Robinson, but Yeldon's impact on what appears to be an improving running game could be a major storyline Saturday.

Here are five other areas of change to watch Saturday:

1)Jared Odrick.If there was one player defensively you wanted to see and didn't in the preseason opener, it was Odrick. He missed the Steelers game with a sore knee, but is expected to play against the Giants. The starting strong-side defensive end, he is key to the run defense – but he is more than that. He has pass-rush ability and is a more dynamic, athletic player than last year's strong-side end, Red Bryant. The Jaguars spent big for Odrick, and while tight end Julius Thomas was perhaps the Jaguars' most high-profile free-agent signing, Odrick was as important in terms of his potential impact. He has looked the part so far in practice and in the team's scrimmage August 8. Saturday should be the first glimpse against an opponent.

2)Roy Miller.The starting nose tackle missed the preseason opener after undergoing offseason knee surgery, and while he will be a game-time decision, there's a good chance he will play Saturday. He and Odrick – along with Otto Dan Skuta and middle linebacker Paul Posluszny – are key to the run defense. The front-line defense allowed a quick score to the Steelers in Preseason Week 1 and then forced five consecutive punts – and did so playing without pretty much its entire front four. Starting tackle Sen'Derrick Marks won't play Saturday and end Chris Clemons won't either, but the return of Miller/Odrick will give the line more of a first-team feel.

3)Tight end.This position won't be dramatically different this week. Starter Julius Thomas, after all, played just two plays last week before sustaining the hand injury that ended his preseason. But this is still a position that figures to be critical in new coordinator Greg Olson's offense with or without Thomas. Marcedes Lewis has had his best camp in at least five seasons and Clay Harbor has continued to show he's a legitimate threat as a move/receiving tight end.

4)Safety.A finger injury to starting strong safety Johnathan Cyprien will keep the third-year veteran out through the preseason, and rookie James Sample is a week away from returning from an offseason broken forearm. That will give the position a backup feel on Saturday with the exception of Sergio Brown, who appears likely to begin the season as the starting free safety. Josh Evans played 33 snaps at safety in the preseason opener and Craig Loston played 44 snaps. Loston is expected to start, and those two will split the majority of the front-line repetitions.

5)Center.No injuries here, and no players returning from injuries, either. What you do have is a change in the starting lineup – and although that change was expected, it still matters. Stefen Wisniewski and Luke Bowanko have alternated working with the starting unit pretty much daily throughout training camp, with the coaches looking to keep the footing in this battle as even as possible. Bowanko started the preseason opener, and considering the what's-fair-is-fair nature of this competition, it's unsurprising that the plan is for Wisniewski to start Saturday. This battle is close and Jaguars Head Coach Gus Bradley said early in training camp he would like to name a starter by Week 3 of the preseason. That's not a hard deadline, but a decision should be coming soon.