INDIANAPOLIS (AP) - Matt Barkley and Landry Jones made some tough calls last season.

Instead of taking first-round money and leaving school early, they decided to stick around, hone their skills, chase a national championship and improve their draft stock.

With the NFL draft about two months away, the two quarterbacks once billed as Heisman Trophy front-runners are now trying to improve to enhance their chances of being selected early.

I've learned a lot in this past year that you can't teach in a classroom,'' Barkley said Friday at the NFL scouting combine.You have to learn through experience in regards to handling adversity at its peak. You have to get guys going in the locker room, in the huddle, on the practice field when you're not playing for the postseason. It allowed me to step up and be that voice.''

It's unclear whether that will help Barkley in a year where there is no clear-cut top choice, even among the quarterbacks.

Scouts saw Barkley and Southern California's shot at a national championship - and his chance for the Heisman - come crashing down in a season that went terribly wrong. Becoming the first quarterback taken in the draft took a hit when he sprained his right shoulder in a late-season loss to crosstown rival UCLA. Barkley never took another college snap, and though he acknowledged Friday the rehab program is on track, critics are already wondering why he won't throw until his March 27 pro day.

Barkley also may find himself answering questions about a locker room dust-up that followed the Trojans' Sun Bowl loss to Georgia Tech.

It was a normal football locker room environment. That happens all the time, trust me. It happens all the time on teams across the country,'' Barkley said.It was nothing out of hand. It was guys exchanging words and wanting to set the record straight. But the captains, myself and some of the other seniors, we had everything under control.''

The concerns about Jones have nothing do with health.

In 2012, he actually threw for more touchdowns, a higher completion percentage and had fewer interceptions and a better efficiency rating than in the previous season. But the perception after Oklahoma fell out of the title chase was that Jones failed to improve his poise in the pocket or his footwork. His performance at the Senior Bowl (3 of 9 for 16 yards with two sacks) raised more red flags.

Jones believes the extra year in college has made him better.

I think I showed the things that I wanted to improve on,'' he said after measuring in at 6-foot-4, 225 pounds in Indy.I shortened my motion and move around in the pocket a lot more than I have been.''

There are so many concerns about this year's class of skill players, some analysts believe the unthinkable could happen: an entire first round without a quarterback or running back selected.

Right now, the top-rated quarterback is believed to be West Virginia's Geno Smith, like Jones and Barkley a drop-back passer, Others expect North Carolina State's strong-armed Mike Glennon to be a fast riser as the draft nears.

The quarterbacks aren't alone.

At running back, the list of potential first-round options essentially ended when South Carolina's Marcus Lattimore shredded his right knee in a gruesome scene Oct. 27. His pitch is that he will be the same spectacular runner when he returns, like two other NFL superstars who came back from devastating knee injuries.

There will never be another Adrian Peterson, but that gives me a lot of motivation knowing that he came back from it. That's what I plan on doing, just coming back better,'' Lattimore said.I feel like we both run hard. (Peterson) runs like nobody is there. He runs with total destruction.

``I feel like if I could compare my game to anybody, it would be Frank Gore. I feel like he's got low pads, he's got great vision, he can see the field and (has) great balance.''

If Lattimore isn't the guy, the next best hope might be record-setting runner Montee Ball of Wisconsin. Critics complain he does not have enough speed to be a breakaway threat or enough size to be a power back.

There's also Alabama running back Eddie Lacy, the SEC championship game MVP, who must show he can stay healthy after a college career that included toe, knee, ankle and foot injuries.

Those guys will at least have a chance to prove themselves on the field at the combine and pro days between now and late April.

Receiver Da'Rick Rogers has the much tougher sell.

Yes, he's talented, but the receiver was booted off the Tennessee roster in late August after failing a drug test, transferred to Tennessee Tech and came out of school a year early.

Those are things that I've been working on since I've left Tennessee. It was a real humbling experience for me,'' Rogers said.I feel like it did help me in the long run. It's sad that it happened like that. For me, personally, it made me change who I was and what I was doing wrong.''

All that's left is for the NFL's decision-makers to render their judgments on the biggest questions of all:

• Has Rogers really made that big a change in six months?

• Can Lattimore be the player he once was?

• And are Barkley and Jones worth high draft picks?

Every year is not going to be the same,'' Barkley said in making his case.You can't get better every single year. It's physically impossible to keep throwing for more yards, more yards, more yards every year. There's going to be some years where it just doesn't click or things don't go as planned.''