I’ve written several posts about how to grade wide receivers and did a three-part series on one ranking system two weeks ago. Grading wide receivers requires one to adjust for era, but there are many different ways to do that.

Calvin Johnson caught 122 passes last year for 1,964 yards and five touchdowns. In 1973, Harold Carmichael had 67 receptions, 1,116 yards and nine scores. Which season was better? You might be inclined to think Johnson’s season was much better regardless of era, but both receivers led their respective leagues in both receptions and receiving yards. But let’s think about it another way.

In 1973, all the players on the 26 teams in the NFL combined for a total of 4,603 catches and 58,009 receiving yards. That means Carmichael was responsible for 1.46% of all receptions and 1.92% of all receiving yards. Of course, with only 26 teams, we need to multiply those numbers by 26/32 make for an apples-to-apples comparison of the modern environment. If we want to transport Carmichael into 2012, that means he needs to be credited with 1.18% of all receptions and 1.56% of all receiving yards accumulated last year. That would give him 128 catches and 1,970 receiving yards, and thanks to recording 1.93% of all receiving touchdowns in 2012, 14.6 touchdowns.

This analysis is actually unfair to active players, as there are more three-, four-, and five-wide receiver sets than ever before. Elroy Hirsch gained 1,495 receiving yards in 12 games — an outstanding rate of production in any era — but that translates to an absurd 2,667 receiving yards in 2012. In Don Hutson’s magical 1942 season, after multiplying by 10/32, he gained 2.3% of the league’s receptions, 2.8% of the receiving yards, and 4.9% of the touchdowns — for a 254/3501/37 stat line.
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