We know that the NFL is a war of attrition. Sure, sometimes teams overcome a slew of injuries to have great years. And some teams are remarkably injury-free -- they're just bad, even while staying healthy. But injuries often help determine the successful teams, and that's true along the offensive lines, as well.

When we put together the preseason magazine, we project each team's five starters. Sometimes it's certain, sometimes there's a lot of guesswork. We never know for sure whose top picks will work out or not, or what trades will take place in July and August. But just past the midway point in the season, we can look at all 32 lines and see which teams have been most gutted by injuries, and which have been least affected. It's not surprising that a lot of better lines show up as the healthiest.

LOST NO STARTERS TO INJURY

Buffalo. Yes, it's true. In Week 9, the Bills started the same five lineman we expected them to start in the preseason. That's right, their line which is on pace to allow 60 sacks, fewer than only Cleveland, is going according to plan.

Cleveland. The Browns have also been healthy on the line. Only issue is they haven't really solved the hole at left tackle left by Joe Thomas' retirement. Second-rounder Austin Corbett flopped, so did undrafted Desmond Harrison. Right now it's former Rams top pick Greg Robinson. Poor line, but healthy.

Detroit. The Lions just surrendered 10 sacks at Minnesota, so bad timing to point out their line has been pretty much healthy. But they've played well for most of the season -- including fronting a greatly improved ground game -- and the line isn't at fault for this team's poor record as much as the run defense.

L.A. Rams. Here we go. Healthy and great.

New Orleans. And again. The NFC's two best teams thus far.

N.Y. Jets. The Jets could stand to be better on the line, but they've been healthy. Upgrades at a couple of spots are likely on the docket for the offseason.

Oakland. Hints that the Raiders planned early on to tank the season were in their questionable decision to start rookies at both tackle spots. Those guys have stayed healthy. The interior of the line isn't bad. But the overall results, thanks to those overmatched tackles, are not good.

Philadelphia. Jason Peters and Lane Johnson have both dealt with injuries along the way, but none have been serious thus far. Carson Wentz is taking too many sacks, but protection hasn't been the major issue; he has a tendency to hold the ball too long.

Seattle. The Seahawks have long struggled for continuity and solid play on their offensive line. They've found it this year -- health, too.

Tampa Bay. Nothing wrong with Tampa Bay's offense. It can't run the ball, but that might have more to do with mindset and scheme than ability on the offensive line, which has been healthy.

LOST ONE STARTER TO INJURY

Arizona. Center A.Q. Shipley tore his ACL early on, damaging the entire line (which was going to be bad even with Shipley).

Chicago. The Bears recently placed Kyle Long on IR with a foot injury. Just the one starter, but he's their best one.

Cincinnati. Bengals have had some banged-up players and underperformers, but the biggest absence has been center Billy Price, who's missed a chunk of games with a foot injury. He could be back this week, which will help the ground game at a minimum.

Denver. The Broncos have had one of the league's best ground games. But center Matt Paradis just landed on IR after breaking his leg, so we'll see how Denver's offense fares the rest of the way.

Green Bay. The Packers have been without Justin McCray for a good chunk of games; they've been using Byron Bell. For the most part, this line is healthy.

Houston. Houston's line isn't good (especially at tackle), but it's been fairly healthy. It lost right tackle Seantrel Henderson to a broken ankle. Debatable whether it's any worse off with Kendall Lamm in that spot.

Jacksonville. Left tackle Cam Robinson was lost for the season early on, and that's been a severe blow to the offense.

Kansas City. Guard Laurent Duvernay-Tardif is the season-ending loss here. The team also lost fill-in Jordan Devey, and has been without Mitch Morse at times. But just the one starter for the season, and that's helped what has been a top-performing line.

L.A. Chargers. Interesting story with the Chargers. Right tackle Joe Barksdale was hurt early on. But the Chargers got better with Sam Tevi there; he's now a fixture. And Michael Schofield has kicked inside to right guard, and he's been very good, as well. Forrest Lamp is on the bench. Sometimes injuries enable you to find a better player, and that seemed to happen with the Chargers.

Minnesota. Vikings have only lost one starter, Nick Easton, for the season. But Riley Reiff, Pat Elflein and Tom Compton have all missed games along the way. The line should be pretty much healthy the second half of the season; Dalvin Cook, too. Things are looking up for Minnesota.

N.Y. Giants. Center Jon Halapio was the only major loss for the Giants, whose other issues are that Nate Solder hasn't been a difference-maker at left tackle, and Ereck Flowers played himself right off the roster after being given one more chance. Front office is at fault more than injuries for this disaster of a line.

Pittsburgh. Marcus Gilbert isn't out for the season, but he hasn't played the last four games, and it's not certain when he'll return. Otherwise, this line is healthy -- and has been dominant, as we saw last night.

San Francisco. Putting the 49ers here because of their guard troubles; Mike Person and Josh Garnett have both battled injuries during the season. But they haven't actually lost a starter for the season, and offensive line is the least of this team's problems.

Tennessee. Titans have been pretty much healthy. But Jack Conklin, coming off a torn ACL, wasn't healthy at the start of the season, and now he's in the concussion protocol.

LOST TWO STARTERS TO INJURY

Atlanta. The Falcons lost both guards to injury, Andy Levitre and Brandon Fusco. Didn't hurt against Washington last week, we'll see if it hurts the offense in the second half of the season.

Dallas. The big one is center Travis Frederick (illness). But both guards, Zack Martin and Connor Williams, have had injuries along the way. Martin is healthy now, but Williams might be headed for IR. He'd been a liability anyway, so there's that.

Miami. This is "so far"; Miami had its starting tackles exit last week's game, but it's not yet clear if those are serious. They lost two interior starters, center Daniel Kilgore and guard Josh Sitton. Kilgore isn't very good and Sitton is probably a little overrated (teams keep cutting him), but we'll see if the tackle injuries end up keeping them out of the lineup.

New England. The Patriots lost rookie Isaiah Wynn, who was probably their preferred starters at left tackle. But Trent Brown, who the 49ers inexplicably gave away, has been fine. Shaq Mason is the other guy who's missed time due to injury, but it's not a long-term deal. Maybe New England more appropriately should be in the "one starter" group.

LOST THREE OR MORE STARTERS TO INJURY

Baltimore. One reason why the Ravens offense has tailed off recently is they're really banged-up on the line. Alex Lewis (neck), James Hurst (back) and Ronnie Stanley (ankle) have all missed time recently. The bye week will maybe help those guys get healthy; can't hurt.

Carolina. Both starting tackles and a starting guard have missed most of the season, and that's after losing Andrew Norwell in free agency. Pretty impressive what Cam Newton and Christian McCaffrey have been able to do given the injuries on this line, and at least one of those tackles (Matt Kalil or Daryl Williams) may be able to return in the next couple of weeks.

Indianapolis. It's impressive how the Colts have played on offense, since they've lost two different right tackle starters (Joe Haeg, J'Marcus Webb) and a guard (Matt Slauson). But the players who have remained healthy -- notably first-rounder Quenton Nelson and second-rounder Braden Smith -- have been excellent. The injury losses haven't been an issue.

Washington. Washington will get Trent Williams back from a thumb injury in three or four weeks, so there's that. But they've lost both starting guards for the season. It hurt them against Atlanta, and it's probably going to continue to be painful the rest of the season.