Barry Sanders was born in 1968. Emmitt Smith was born in 1969. The next two years were pretty quiet — Dorsey Levens and Garrison Hearst were born in ’70 and ’71 — but business was about to pick up. Terrell Davis and Jerome Bettis were born in 1972, and Curtis Martin, Eddie George, Marshall Faulk, and Priest Holmes were all born in 1973. That’s a 6-year period that gave us some of the most important running backs in NFL history.

And it came at a really important time. Because the previous five years were not nearly as fruitful.

• In 1967, there were no notable ^[1]Okay, this sounds kind of mean, but I mean notable in the sense of having historical importance to the game of football. running backs born.
• In 1966, Thurman Thomas was born, but other than him, not much else.
• In 1965, there were no notable running backs born.
• In 1964, Neal Anderson ^[2]Note that the notable bar is very low. was born and that’s about it.
• In 1963, Rueben Mayes was the most notable running back born.

In 1962, a pair of notable backs were born, but their names certainly outshined their production (as measured by rushing yards Gray Ink).  Herschel Walker was a great running back in the USFL and a great receiver in the NFL, but he had just one top-5 rushing season and just one more top-10 rushing season.  Earnest Byner was also born that year, and while he ranks 41st in career rushing yards (and 16th when he retired), he had only top top-10 rushing seasons in his career.

1961 was about an average year: no superstars, but Curt Warner and Christian Okoye were both born. But it was 1960 that was the banner year: it gave us not only Eric Dickerson, but Gerald Riggs, Joe Morris, Marcus Allen, and Roger Craig.

So if you look at trailing 5-year periods, the years from ’61 to ’65, ’62 to ’66, and ’63 to ’67 look pretty rough. But the periods from ’65 to ’69 and ’66 to ’70 look really good. I tried to come up with a very simple measure of running back talent born each year, and I decided to just use a Gray Ink test based on rushing yards. So I gave a player 10 points for leading the league in rushing yards, 9 points for finishing 2nd, 8 for finishing 3rd, and so on. For these purposes, I combined the AFL and NFL. Then, I summed the number of points of gray ink assigned for each birth year.

1965 ^[3]Merril Hoge (3,139) and Rod Bernstine (2,990) were your career leaders in rushing yards born that year. and 1984 ^[4]Pierre Thomas (3,809), Michael Bush (3,250) and LenDale White (2,349) were your career leaders in rushing yards born that year. were the only years with 0 points of Gray Ink. The best year? 1968 comes in second, as Terry Allen, Chris Warren, and Barry Foster joined Sanders. But it was 1954 that stands out as the best year, which is when Walter Payton (if you believe he was born that year), Tony Dorsett, Wilbert Montgomery, and Mike Pruitt entered the world.

I decided to graph the Gray Ink by birth year for each trailing 5-year period. Take a look:

What do you think? Is this random variance? Is there some explanation? Is it a coincidence that the period from the late ’60s and early ’70s was so good, and the period from ’61 to ’67 was so weak?  Or is that correlated — that the running backs born in the late ’60s found it easier to dominate because the prior class was weak?

Please leave your thoughts in the comments. The inspiration for this post came from this article on the lost generation in men’s tennis from Andrew Burton (h/t Carl Bialik at 538). Are there similar lost generations in NFL history for specific positions?