What is "pale in comparison?

What year is the cutoff line for a 1:1 comparison of NFL statistics?

• It isn't fair to simply compare throwing statistics for modern quarterbacks to those from, for example, the 1970s. The game has changed too much since that time period to make a 1:1 comparison. Where is the logical cutoff point where such comparisons become invalid? Does it change for different statistics - perhaps the defensive comparison cutoff should be further back than the offensive?

• Answer:

  1978 is one clear demarcation line.   That year, pass interference rules changed to disallow defensive contact with receivers beyond five yards from the line of scrimmage.  Previously, contact had been allowed anywhere downfield until the ball was thrown.   This massively changed the game. Advanced NFL Stats is fast becoming my go-to site for questions like this -- its founder, Brian Burke (http://www.advancednflstats.com/2008/02/about-author.html) has done some amazing research directly relevant to this question. Brian's full essay (well worth reading)  is here: http://www.advancednflstats.com/2010/01/run-pass-balance-historical-analysis.html But two exerpts of interest are these graphs -- each of which shows why the 1978 rules changes mattered so much. First, yards per play for running and passing almost immediately diverge wildly in 1978.. see below: Similarly, look at what happened to play calling after 1978: (Side Note: Carson Cistulli, also of Advanced NFL Stats, recently wrote an inetersting piece about in-game win probability, and how it impacts play calling -- this is a great read, too: http://www.advancednflstats.com/2011/11/runpass-distribution-by-win-probability.html?utm_source=twitterfeed&utm_medium=twitter  )