INDIANAPOLIS, Ind. – Welcome to the day of unknowns.

That's the lead to this View from the O-Zone for several reasons, but the biggest reason is that on this day from the 2018 NFL Scouting Combine we're talking offensive line.

And there may be no bigger unknown in the NFL these days than that.

Thursday was a big day for big guys at the combine. They lifted a lot of weight a lot of times and spoke to the media from behind elevated podiums. All of this is pertinent to Jaguars observers because there seems at least a relatively good chance at least one of these players could be selected by the Jaguars in the upcoming 2018 NFL Draft.

But to try for specifics when it comes to the offensive line. …

To try to see what the NFL wants in that area …

"That's a helluva question," New York Giants General Manager Dave Gettleman said this week when asked if the NFL needed to adjust to how offensive lineman entered the league.

And indeed it is a … well, tricky … question.

"At the end of the day if you watch football, obviously the college game a lot of it is really different," Gettleman said. "If you watch how it's evolved, it's changed in style."

The general consensus is offensive line play across the NFL is down. Fans and media who closely observe their own teams as often as not can pick out two or three linemen they see as weaknesses and who need immediate replacing.

Where to find said replacements is trickier. Front-line offensive tackles are a rare free-agent commodity and relatively few front-line interior players – guards and center – hit free agency. Truly dominant offensive linemen appear rarer and rarer.

The Jaguars this past season in a sense reflected the issue: the offensive line improved in 2017 over 2016. The team led the NFL in rushing by a wide margin, and the offense allowed the fewest sacks in franchise history. You don't accomplish those two feats with a weak offensive line.

Still, quarterback Blake Bortles was under pressure in a lot of key situations, particularly at critical times in the AFC Championship Game.

The running game also struggled at times in key situations to run when it needed and wanted to run. Rookie running back Leonard Fournette rushed for under four yards per game for the season, and late in the season the run game at times was not as dependable as would be ideal.

The Jaguars therefore enter the offseason as a team that many believe will try to upgrade the offensive line, with perhaps left tackle Cam Robinson and center Brandon Linder being the two players most "set" at their respective positions.

Could the team sign a free-agent guard or draft one, or perhaps two?

Could a right tackle be a possibility? That seems less likely with the presence of veteran right tackle Jermey Parnell, but a young player at the position could prove enticing.

On that front, Thursday at the combine – while a day of unknowns – is equally intriguing. There appears likely to be good offensive linemen available when the Jaguars select No. 29 overall in the upcoming draft, and No. 29 overall could be an ideal time to select one.

While left tackle often is a position NFL purists prefer in the Top 10, an interior lineman or a right tackle often seems a better fit late in the first round.

An early combine-week preview of the linemen here: 

Notre Dame guard Quenton Nelson is the consensus best offensive lineman here, and is expected to go in the Top 10. That's rare for a guard, but he's considered a can't-miss player worthy of the selection.

"My mindset is being dominant," he told reporters Thursday.

After that? 

Well, after that there's a lot of disagreement and a lot of thought that a lot of players could be available for the Jaguars at No. 29. Ohio State guard/center Billy Price has appeared in mock drafts at No. 29, as have Georgia guard Isaiah Wynn and UTEP guard Will Hernandez. 

Wynn on Wednesday looked the part, and talked of his athleticism and of being able to play multiple positions.  Nelson as expected looked the part, too, and said he believed it was right considering the quality of interior defensive players in the NFL that he be considered Top 5.

Tackle prospects such as Mike McGlinchey of Notre Dame, Orlando Brown of Oklahoma and Connor Williams of Texas also drew interest Thursday – and could draw interest from the Jaguars in April. They looked the part Thursday. They're intriguing.

Will they draw the interest of the Jaguars? Can they make the adjustment to the NFL?

That's a … well, tricky … question.