JACKSONVILLE – Blake Bortles matters to the Jaguars a great deal.

That's obvious in the short- and long-term, but NFL Films senior producer Greg Cosell said Wednesday the Jaguars likely will have another priority next season, too.

Yes, Bortles' development as he enters his second season as the Jaguars' starting quarterback is important, and Cosell on Wednesday reiterated his recent thoughts that the fundamentals work Bortles is doing this offseason is very, very important.

But Cosell said for the Jaguars to be productive next season more is needed.

"I think they're going to need to run the ball; I think last year didn't work out the way they wanted it to," Cosell said Wednesday during an appearance on Jaguars.com LIVE.

The Jaguars finished 21st in the NFL in rushing last season with a backfield that featured Denard Robinson starting nine games, Toby Gerhart starting seven and Storm Johnson starting one game as a rookie.

Cosell raised the idea of upgrading the backfield in the offseason.

"Probably their most talented back is Storm Johnson," Cosell said of the 2014 seventh-round selection from Central Florida. "I don't know if they're going to go into the season with the same group of backs they had last year or if that's a position they're going to look at.

"It's become very easy to say over the last several years that the running back position is marginalized and anybody can play running back. I'm not sure I'm a believer in that point of view. I think if you really want to run the ball as your offensive foundation then you need a good back.

"I'm not suggesting they take a back at No. 3 (overall in the 2015 NFL Draft), but if you truly want the offense to start with the run game, then you need a good back."

Cosell, widely considered one of the better judges of talent among national media members, also spent time Wednesday discussing Bortles, the No. 3 overall selection in the 2014 NFL Draft who started the final 13 games of his rookie season.

Cosell said while Bortles "clearly needs to improve in many areas," he said that wasn't unexpected, noting the Jaguars' original plan was to have Bortles back up Chad Henne much or all of last season. He also said Bortles' fundamentals declined as last season continued, something Bortles has discussed several times publicly and something on which he is currently working in California.

"He's a big, athletic kid who throws it pretty well," Cosell said. "His mechanics have to stay consistent and stable, and when they don't he doesn't throw it quite as well. He made a number of throws last year that were clearly big-time throws and you said, 'Those were NFL throws.' You really like to see that.

"He has some movement to him. You can do as an element of your offense some read-option principles, and concepts here and there, which do stress defenses, but when all is said and done this league is still about throwing the ball from the pocket, and ultimately that's where his improvement needs to come."

Cosell also said he didn't see the Jaguars' change in offensive coordinators last month as a huge issue for Bortles. The Jaguars dismissed Jedd Fisch as coordinator and replaced him with Greg Olson.

"It's not like he played in one system for eight years, and all of a sudden you're changing everything," he said. "You would have liked stability. Everybody would prefer that, but I don't think that's a killer deal right now."

Also on Wednesday:                     

*Cosell said he was in the minority when it came to Southern California defensive tackle/end Leonard Williams. While some project Williams as the best player in the draft and perhaps a once-in-a-generation talent, Cosell said, "I don't see any of that." Cosell said he has watched four games of Williams, calling him "a nice player" and adding, "I don't think he's special at this point. He's not a true quick-twitch guy. I think he has a tendency to play high. I don't think he's a natural pass-rusher at this point and I don't think he played particularly well in space." …

*Cosell also said Williams was a "flash player who made the occasional impressive play," and said the key to evaluating Williams is what you believe he will be in two or three years. "As far as what he is right now, he's not a three-technique," Cosell said. "When you think of that, you think of a Gerald McCoy coming out of Oklahoma or a Sheldon Richardson coming out of Missouri. He's not that guy right now." …

*Cosell also discussed the quarterbacks at the top of the draft, Jameis Winston of Florida State and Marcus Mariota of Oregon. Of Mariota's transition from a spread offense in college to a pro-style system, he said, "You don't try to be negative, but you look at what you see on film and what you don't see on film. What Mariota's used to is a precisely-timed passing game where the ball comes out quickly to schemed-open receivers." Cosell added that Winston "has run a pro passing game … he understands all that. It's built into how he intuitively plays the game. He's going to have to speed up some things, but as far as understanding the concepts Winston is far advanced." …