JACKSONVILLE – The mission was real, and it sure wasn't easy.

And admit it:

You didn't think Denard Robinson could do it. If you did, you were in a minority who thought the former University of Michigan quarterback could be an effective NFL running back.

But before his season ended this week, the likeable, personable, talented second-year veteran proved he could be just that.

He did it because he worked at it.

He did it because he believed in himself when many didn't.

Because he did it, he's one of the most notable success stories of the Jaguars' 2014 season. And because he did it the Jaguars have a player they believe could be a significant part of their offense and a playmaker for the foreseeable future. And boy did they need that.

And even though he accomplished all of that – and even though by any measure the season was a success – this was still a tough week for Robinson.

It's always tough when you can't finish what you started.

"Of course, I'm disappointed," Robinson said late this week in the EverBank Field locker room. "It's tough, because you want to finish the season out, to be battling with the guys. It's a hard pill to swallow."

His assessment of the season that ended with a foot sprain sustained against Houston this past Sunday?

"Pleased a little bit – but not satisfied," Robinson said. "You still have that taste in your mouth that you have unfinished business."

This was Thursday afternoon after practice. Robinson leaned on crutches as he spoke, a boot protecting the mid-foot sprain in his right foot. He spoke as his teammates filtered out of the locker room toward a meeting. He hadn't attended practice that morning, which meant he wasn't part of the day-to-day routine anymore – a weird feeling after months adhering to a regime.

Still, Robinson was around. There was nowhere else he wanted to be.

"I've got to go back in, hang out with the guys, and keep them going," Robinson said.

How much difference can a few months make in an NFL season?

All the difference imaginable is all.

The player leaning on crutches and talking about joining his teammates Thursday was a player who very well may have been the Jaguars' best offensive player this season. He certainly was that for a few weeks.

He also is a player who matters very much to this offense moving forward.

A few months ago that wasn't the case.

Shoot, a few months ago there were those who wondered not only if Robinson could have a significant role this season, but if he would have a place on the roster.

That's how much the former University of Michigan star struggled as a rookie in 2013.

Robinson struggled to find a position as a rookie, working at wide receiver. And running back. And punt returner. And a little at kick return. And at Wildcat quarterback.

He also struggled with the aftereffects of a college injury that damaged the nerves in his right hand enough that it made it difficult to grasp the football during his rookie season. He played sparingly as a rookie, and when he did play he struggled significantly with ball security issues.

That story has been well-documented, and what also has been well-documented – and what is much happier for Robinson – was what he did this season.

This wasn't an overnight success story. He started the season behind Toby Gerhart, who signed as an unrestricted free agent in the offseason. When Gerhart struggled early, it was rookie Storm Johnson who the Jaguars first tried in his place in Week 6.

Robinson's chance came the next week, and he took full advantage, turning his first week as the No. 1 back into a 22-carry, 127-yard, one-touchdown day against Cleveland and following that with an 18-carry, 108-yard performance against Miami that solidified his status as the starter.

Robinson finished the season with 582 yards rushing and four touchdowns on 135 carries, and while the Jaguars' run offense struggled in recent weeks, Robinson overall showed he can be an effective back in the NFL. He added weight, maintained that weight, and ran better between the tackles than most believed.

He has work to do with blitz pickup, but the improvement he showed in his first full year at the position was by any measure remarkable.

"I think I proved to people who didn't believe in me, but I really wanted to prove it to the people who believe in me," he said. "I felt like I did some things, but I think I can accomplish more things."

The next step for Robinson? He must heal, and then he must improve as a pass-blocker, as a runner … well, he'll be entering his second season, so he'll need to improve at everything.

Is he The Guy at running back in the sense that he will get every carry, series after series? Likely not. Few teams have that guy anymore. But a bona fide NFL running back, a guy who can carry a team for stretches, be productive and make big plays …

That's what the Jaguars need from Robinson, and that's what he became this season.

Mission accomplished. So far.