It’s commonly said that the Dallas Cowboys have the best offensive line in the league.

That’s not the case anymore, according to Pro Football Focus.

PFF put out rankings of all 32 NFL offensive lines and the Cowboys are not ranked first. Instead, the Philadelphia Eagles take the No. 1 spot.

Out of all the offensive lines in the NFL, the Eagles currently have the fewest holes. Their biggest question mark heading into 2017 is center Jason Kelce, who is a former PFF All-Pro (2013) in his own right. They also have dominant players like Lane Johnson, who was the best right tackle in the NFL a season ago when on the field.

Here’s how the Eagles’ offensive line graded out by PFF last season.

Jason Peters - 8th out of 78 tackles

Allen Barbre - 23rd out of 72 guards

Jason Kelce - 27th out of 38 centers

Brandon Brooks - 4th out of 72 guards

Lane Johnson - 9th out of 78 tackles

Certainly not a bad group.

Kelce is indeed the biggest question mark on the Eagles’ offensive line. There was a report that the team was considering moving on from him this offseason. That clearly didn’t happen because he’s still here. Kelce has been a good player for most of his career but he hasn’t played at his peak for the past two seasons. Kelce turns 30 in November.

The other spot in question on the Eagles’ offensive line is at left guard. Isaac Seumalo, a third round pick from the 2016 NFL Draft, could be the starter there. He took a lot of first team reps at that spot this spring. He also split time with Barbre, however, so there’s some competition there.

Peters and Johnson are two very good tackles. Peters is a future Hall of Famer on the back end of his career while Johnson is an ascending talent. Johnson is arguably the Eagles’ best player on the entire offense. Philadelphia was 5-1 with Johnson in the starting lineup last year and 2-8 without him.

Brooks was a nice free agency signing for the Eagles last year. They desperately needed help at guard and he immediately proved to be an answer at the position.

The Eagles’ offensive line strength goes beyond their starters. They have pretty good depth, too. Philadelphia offensive coordinator Frank Reich touched on this topic this during spring practices.

I love our O-line. I thought last year felt the same way. We just have more depth and more strength this year. I think it's one of the strong points of our team. I think we have great leadership there. I think [C] Jason Kelce is a great leader up front. He's a quarterback up there. The guy is as smart of a football player as you can get, and he just is very versatile in the things that he can do for us up front. I think we're really good at the tackle position, obviously – two of the better tackles in the league – and then our guard situation is … I mean, our second-team guards should be starting on most teams. So it's a very competitive room, really good room; good for our team.

The loser of the Seumalo/Barbre battle will likely be the top backup off the bench. Seumalo could also take over for Kelce if the veteran struggles and/or gets injured.

Then there’s Stefen Wisniewski, who the Eagles re-signed this offseson to a deal worth $9 million over three years. Wiz, currently projected to be a backup, started six games for Philly last season. He’s started 83 games over his career. That’s one experienced backup.

Chance Warmack is another experienced backup at guard. The former No. 10 overall pick in the 2013 NFL Draft has made 48 starts over four seasons. Although he was a bust for the Titans, he’s now reunited with his former college offensive line coach: Jeff Stoutland.

The Eagles’ swing tackle, if it’s not Barbre, could be second-year blocker Halapoulivaati Vaitai. The man they call “Big V” got off to a rough start as a rookie in 2016 but he settled in after that.

I don’t know if the Eagles truly have the NFL’s best offensive line, but it’s certainly a good overall situation for Philadelphia. The starters are accomplished and the backups have a lot of experience. Even if a player such as Kelce turns out to be a weak point, the Eagles have ample depth to replace him.

Getting back to the Cowboys for a second, it’s not just that they’re not the league’s top offensive line anymore. They’re not even in the top five. They fell all the way down to No. 9 in the rankings. PFF explains why:

They’ve been the class of the league for so long, but a line can only survive so many hits. Ronald Leary and Doug Free weren’t at the caliber of Tyron Smith, Travis Frederick, or Zack Martin, but they were quality players in their own right. The big question mark is La’el Collins moving to right tackle. Tackle was his more natural college position, but his below-average performance at guard isn’t too encouraging.

Collins has a lot to prove at tackle in the NFL. He’ll be going up against some strong edge rushers now including Philadelphia’s own Brandon Graham. But Collins isn’t necessarily the biggest concern. Dallas is potentially starting Jonathan Cooper at left guard. The same Jonathan Cooper who was traded away by the Cardinals and cut by the Patriots and Browns.

The Cowboys’ offensive line is so critical to the team’s overall success. It’ll be interesting to see how Dak Prescott and Ezekiel Elliott fare with a seemingly weakened unit up front.

As for the rest of the NFC East, the Washington Redskins check in at No. 11.

Continuity doesn’t really play a role in theses rankings, but if it did the Redskins would get a bump. They bring back the same starting five from a season ago and a line that had four of the same five starters in 2015. Understanding what the man next to you is going to do isn’t necessarily something we can capture in a grading system, but it certainly is important to an offensive line’s effectiveness.

The Eagles have failed to pressure Kirk Cousins effectively in recent years. As a result, the Eagles haven’t been able to beat Washington. They have a good offensive line for sure.

You know who doesn’t have a good offensive line, though? That’s right, the Giants.

Few teams have larger chasms on their offensive line than the left side of the Giants line. Ereck Flowers has had serious issues in pass protection over the course of his career and led all tackles in pressures allowed as a rookie. Next to him is left guard Justin Pugh who has been a top-15 guard when healthy over the past two years.

New York has a lot of weapons in the passing game: Odell Beckham Jr., Brandon Marshall, Evan Engram, etc. But how much will that really matter if Eli Manning, who struggled last year, doesn’t have time to get the ball to them?

The Eagles have beaten the Giants in 14 out of their last 18 matchups. I think Philadelphia’s pass rush could cause some serious issues for New York’s line this season.