We've got this little stat we use in Football Outsiders Almanac each year called the offensive line continuity score. A guy named Jason McIntyre came up with the idea for an article in one of our early books, and we still track it every year. We just ran the numbers for 2014, and wow, last year's OL continuity scores are really low.
As in, we didn't realize this before, but there was not a single team in the NFL that started the same five offensive linemen in all 16 regular-season games.
Continuity score takes three variables: number of starters used, number of times the starting line changes between games, and longest stretch starting the same five guys in the same five spots.