by Vincent Verhei

Is the quality of offensive line play declining in the NFL? That's a subjective question, one that's hard to answer numerically.

Are offensive linemen shuffling in and out of the starting lineup more frequently now than they were at the turn of the century? That's an objective question, one with a crystal-clear answer: Hell, yes,

Jason McIntyre McKinley developed a metric to measure offensive line continuity back in the early days of FO (when FO Almanac was still Pro Football Prospectus) and we have since gone back and calculated it for every team since 1999. The continuity scores are based on three variables: number of starters used; number of week-to-week changes in starting lineups; and the longest starting streak of any one five-man unit. A team can earn a maximum of 16 points in any one category (one point per game), meaning a team that started the same five linemen in all 16 games would get a perfect score of 48.

Only one team got a perfect score in 2016, and that team had the league's best offense and nearly won the Super Bowl. Atlanta's starting quintet of Jake Matthews, Andy Levitre, Alex Mack, Chris Chester, and Ryan Schraeder started all 16 regular-season games. Their perfect score doesn't even count that they each started all three playoff games as well.

No other offensive line had a perfect lineup in 2016. In fact, nobody else came close. The next-highest scores belonged to New England (perhaps not coincidentally, Atlanta's Super Bowl opponent) and Cincinnati, who were tied for second at 38. It was the first year since 1999 that only one team had a continuity score of 40 or more, and the fourth year in a row the number of such teams has gone down. Meanwhile, seven teams had continuity scores of 25 or less. That's fewer than the nine such teams in 2015, but still more than any other year on record. The average team's continuity score in 2016 was 29.8 -- the first time on record the average score has dropped below 30, and the third straight year the average score has dropped.

NFL Offensive Line Continuity, 1999-2016 Year Teams Avg. Cont. Score 40 or higher 25 or lower 1999 31 33.4 1 0 2000 31 35.5 10 4 2001 31 34.7 5 3 2002 32 31.8 3 4 2003 32 34.5 10 5 2004 32 33.3 5 2 2005 32 34.8 9 3 2006 32 32.9 5 2 2007 32 34.8 9 3 2008 32 34.4 7 3 2009 32 31.5 2 4 2010 32 32.5 5 6 2011 32 32.8 5 5 2012 32 32.5 7 6 2013 32 33.4 6 4 2014 32 30.7 3 6 2015 32 30.3 2 9 2016 32 29.8 1 7

Given the league-wide slipping of offensive line continuity, what New England did in 2016 was pretty special. As mentioned, they were tied for second in continuity score, but that's underselling their stability by the end of the season. Nate Solder, Joe Thuney, David Andrews, Shaq Mason, and Marcus Cannon started each of the Patriots' final 14 games, including the playoffs. That's even more impressive considering what the team had done the year before. New England's 2015 continuity score of 2015 was just 15, the lowest we have ever measured. The Patriots' 23-point improvement from one year to the next was the biggest on record, and it came in a year when league-wide continuity continued to fall.

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Cincinnati, the team that tied New England for second place, got 16 starts each from Andrew Whitworth, Russell Bodine, and Kevin Zeitler, plus 14 from Clint Boling and 12 from Cedric Ogbuehi. We'll see how they cope in 2017 with Whitworth joining the Rams and Zeitler leaving for Cleveland in free agency. Tied for fourth at 37 were the Cowboys and Chargers. Like Cincinnati, the Cowboys will have to deal with some talent drain, as Ronald Leary (12 starts last season) signed with Denver and Doug Free (16 starts) retired. A healthy La'el Collins would certainly help -- the second-year guard played only three games last season. As for the Chargers, they got 16 starts apiece from Orlando Franklin, Matt Slauson, D.J. Fluker, and Joe Barksdale, but Fluker and 12-game starter King Dunlap won't be joining the team in Los Angeles -- Fluker now plays for the Giants, while Dunlap is presently unsigned.

At the other end of the spectrum we find the New York Jets, whose continuity score of 20 is among the five worst we have ever found. The quarterbacks, as usual, got all the attention for New York's struggles, but let's not overlook that tackles Ryan Clady and Breno Giacomini and center Nick Mangold combined for only 20 starts, and were never all on the field together.

The Jets are followed closely by the Saints at 21, though in this case that's probably over-rating the instability of the line in New Orleans. Center Max Unger, right guard Jahri Evans, and right tackle Zach Strief missed just one start between them. Left tackle Terron Armstead, though, started only seven games, and the Saints never quite figured out what they wanted to do in his absence. Senio Kelemete started two games at left tackle and seven at left guard, while Andrus Peat started seven games at left tackle and eight more at left guard. That includes six games where Peat was at tackle and Kelemete was at guard, and two games where they switched spots. Moving guys from the bench to the field and back probably didn't help things in New Orleans, but at least it was usually the same two guys going back and forth and not a never-ending parade of new faces.

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Our bottom five is rounded out by Arizona, Minnesota, and Cleveland. The Cardinals started five different players at right guard alone in 2016 (insert joke about Cleveland quarterbacks or Spinal Tap drummers here), and it's very unclear who will be playing there this fall. Speaking of Cleveland, there is a reason the Browns gave Kevin Zeitler and J.C. Tretter a combined $29.5 million in free agency. As for Minnesota, they were the anti-New England. The only team to post a perfect continuity score in 2015, they dropped 25 points (tied with the 2014 Bears for the biggest decline in our files) in 2016. Injuries to starting tackles Matt Kalil and Andre Smith left Minnesota scrambling to fill holes all year, with T.J. Clemmings starting at both tackle spots, Jeremiah Sirles starting at both right tackle and left guard, and Joe Berger starting at center plus both guard spots. (Let's not forget that Minnesota's perfect continuity score in 2015 does not mean they had perfect health. Starters Phil Loadholt and John Sullivan went down for the year in the preseason, with backups Mike Harris and Clemmings going the whole season in their places.

The following table shows offensive line continuity numbers for all 32 teams in 2016. As the supply of offensive line continuity around the league goes down, it's value goes up. Exactly half the NFL's teams had a continuity score of 30 or higher, and nine of those teams made the playoffs. However, only three of the 16 teams with continuity scores worse than 30 qualified for the postseason.