They can be underrated or taken for granted, but offensive lines are critical components to offensive performance. Every year some team sees its offense struggle or falter due to a critical shortcoming up front. Dallas has had probably the league's very best offensive line in recent years, so you have to wonder how recent developments will impact the team.

Travis Frederick has been diagnosed with an auto-immune condition called Guillain-Barre Syndrome. Return to the field uncertain, but injured reserve is a possibility (if not a likelihood). He was maybe the game's very best center, so the dropoff to backup Joe Looney is precipitous. Factoring that in, Dallas goes from having our top-ranked line to one that is probably more of a top-10 group. Dallas has a bit of question at left guard, too, where rookie Connor Williams takes over. Still very strong at other spots, but not the dominant unit it's been.

With Dallas slipping, New Orleans moves into the top spot, slightly ahead of Philadelphia. Some may have seen center Jason Kelce leaving the last exhibition game with what was called a lower back injury, but he's fine. Those are our top two lines at this point, with Pittsburgh, Atlanta and the Rams rounding out the top 5. Then Dallas.

Carolina is the other line that's been gutted by injury, and that's after losing Andrew Norwell in free agency. It lost right tackle Daryl Williams for the season, and now Matt Kalil has undergone a knee scope that's expected to keep him out of the start of the season. Norwell's projected replacement, Amini Silatolu, will miss at least the start of the season after knee surgery.

New England first-rounder Isaiah Wynn wasn't definitely going to start, but it was possible. Instead he's out for the year with an Achilles injury; it will be Joe Thuney in that left guard spot.

The Vikings won't have center Pat Elflein at the start of the year; they acquired Brett Jones from the Giants to open in that spot. But they do think Elflein will be able to play early in the season, just not Week 1. Minnesota's line has taken several hits, including guard Nick Easton undergoing neck surgery, leaving them weaker at that spot.

Several teams sustained preseason tackle injuries of unknown severity: Cordy Glenn of the Bengals, Donovan Smith of the Bucs, and Denzelle Good of the Colts. (Anthony Costonzo is also dealing with a hamstring injury for the Colts.) Typically we'll lower the grade of those players until their health status is clearer, causing the line to slip accordingly. Indianapolis can't get the line in front of Andrew Luck sorted out, despite adding Quenton Nelson.

Rankings are below; colorful table posted on our Facebook page showing our evaluation of each player.

OFFENSIVE LINE RANKINGS
RkTeam
1.New Orleans
2.Philadelphia
3.Pittsburgh
4.Atlanta
5.LA Rams
6.Dallas
7.LA Chargers
8.Oakland
9.Green Bay
10.Tennessee
11.Jacksonville
12.Washington
13.Kansas City
14.New England
15.San Francisco
16.Baltimore
17.Tampa Bay
18.Detroit
19.Cleveland
20.NY Giants
21.Carolina
22.Chicago
23.Minnesota
24.Indianapolis
25.Seattle
26.NY Jets
27.Denver
28.Cincinnati
29.Miami
30.Houston
31.Arizona
32.Buffalo

--Andy Richardson