ESPN NFL Insider John Clayton has a theory. If the combined age of the starting offensive line is greater than 150 years, expect an eventual transition. Clayton calls it the "Theory of 150". From a certain perspective, it makes sense. If the combined age is greater than 150 years, then common sense (and basic math) dictates that the average age is greater than 30 years old, an age often viewed (generically at least) in decline. Clayton writes:
If a team lets its starting offensive line exceed the total age of 150 years for five starters, the clock is ticking on its remaining success. Three teams hit that mark over a three-year period -- the Bears, Washington Redskins and Dallas Cowboys. The New York Giants hit the 150 mark a couple years ago and, even though they won a Super Bowl, they had concerns along the offensive line.
Kevin Seifert rightly concludes that the "cumulative age of 150 means an average age of 30 for five starters, an intuitive if arbitrary benchmark for signaling transition."
There's a certain logic to it. But enough to merit change? Much like the theory of mega-million contracts for running backs, it's based on a logical forecast towards transition without a foundation towards consistency (every case invites individual merits). Maybe it's just a foregone conclusion. Once a player reaches the 30-year old benchmark, obviously they're on the tail-end of their respective NFL careers. It's what happened with Willie Anderson when age invited the prospects of injury and he was thus released in 2008. The Bengals didn't improve their lot with Stacy Andrews and few would argue that Andre Smith today is that much of an upgrade over a 30 or 31 year-old Anderson.
Based on the projected starting lineup, the Cincinnati Bengals offensive line currently has a combined age of 136 years old -- Kyle Cook (28), Travelle Wharton (31), Kevin Zeitler (22), Andre Smith (25) and Andrew Whitworth (30). Save for Cook celebrating a birthday two days before training camp, that will be the combined age when the team starts the season against the Baltimore Ravens on Monday Night Football. That number surpasses the 150 milestone in three seasons.
Cincinnati's starting offensive line in 2005 was perhaps one of the league's best, led by First-Team All-Pro Offensive Tackle Willie Anderson. The combined age of that unit was 145 years -- Rich Braham (35), Levi Jones (26), Willie Anderson (30), Eric Steinbach (25), Bobbie Williams (29).
The Theory of 150 is a reasonable system to plan the team's eventual transitions, but not enough to warrant changes when a team reaches "150".