By Cold, Hard Football Facts contributor Jonathan Comey
There have been better running backs in the NFL than Craig "Ironhead" Heyward, but very few bigger – and even fewer that were bigger and better.
Heyward, pictured here in all his oversized glory, died in late May after a long battle with cancer. His death prompted us to take a look at the effectiveness of big backs in the modern NFL. After digesting all the data – and a couple extra beef tongue sandwiches in Ironhead's honor – we discovered that big backs are big in reputation only. Their onfield production leaves a lot to be desired, much like, we also discovered, beef tongue without mustard and sauerkraut.
Ironhead was a guy who would have squeezed in well with the trolls at the Cold, Hard Football cardboard-box world headquarters – at 5-11, 260 pounds, he looked more like a couch potato than an athletic NFL skill player. But he had the skills to run for 1,083 yards with Atlanta in 1995 and more than 4,000 yards in his 11-year career.
If he had come of age in the 1950s, Ironhead probably would have been a defensive lineman, or possibly a center – and a big one at that. Consider Hall of Fame center Frank Gatski, who anchored the line of the Cleveland dynasty of the 1940s and 50s. He punched in at just 233 pounds.
But running backs, like all NFL players, have been getting bigger over the years. There has been a glut of "Big Backs" to hit the NFL over the past 10 to 15 years. The undisputed greatest Big Back of all time, Jerome Bettis, retired at the end of his Super Bowl-winning 2005 season with Pittsburgh.
The first Big Back to make his mark on the NFL was Hall of Famer Bronko Nagurski, who was a load at 228 pounds back in the 1930s. He was monster in his day and bigger than many linemen of the era – his contemporary, Hall of Fame guard Mike Michalske, was a petite 210 – and supplemented his income as a wrestler when he wasn't playing football (that's Nagurski in his nifty wrestling trunks).
Then it was Paul "Tank" Younger, who weighed 230 pounds and sent bodies flying during the 50s. Younger was so big for his time that he began his college career as a tackle at Grambling. Coach Eddie Robinson put him in the backfield. In 1949, the L.A. Rams made Younger the first player drafted out of a traditionally black university.
And then there was Cookie Gilchrist, who made four straight AFL Pro Bowls for Buffalo and Denver from 1962-65 while tipping the scales at 251 pounds and redefining just what BIG meant as a running back.

Since then, there has been a steady stream of good Big Backs who have attempted to roll through the NFL. Some – like Ironhead Heyward or Christian Okoye – have larger-than-life reputations. People remember the highlight reels of Okoye, the "Nigerian Nightmare," barrelling over opposing defenders.
But those highlight-reel memories belie the Cold, Hard Football Facts: Few big men have ever become elite NFL running backs, proving that bigger is not always better – at least when it comes to ballcarriers.
In fact, Bettis is the only transcendent Big Back in modern NFL history. The others muddled through journeyman-like careers that were, in some cases, highlighted by brief flashes of brilliance. Even Bettis' performance was more industrial than spectacular. This future first-ballot Hall of Famer never led the league in rushing. The closest he came was a second-place, 1,429-yard performance during his rookie campaign in 1993. He averaged just 3.9 YPC over the course of his career and exceeded the 4.0 YPC mark in a season just four times in 13 years.
What Bettis did have is an unusually stout constitution. He was simply able to pound away at opposing defenses longer than any other Big Back in history. He rarely missed a game. In fact, when you take into consideration his running style, you could argue that Bettis is the most durable ballcarrier in NFL history. He played in 192 of a possible 208 career games, and started 153.
We compiled a list of the Top 10 Big Backs of all time, ranking them based on career rushing totals. We defined "big" as any back who weighed more than 240 pounds. If you're wondering how big 240 pounds is, consider that Earl Campbell – a gridiron bowling ball who was big by any normal person's definition – was listed at a mere 232 pounds.
While the list of solid 240-plus pounders has grown along with everything else in the NFL, the list of all-time great 240-plus ballcarriers remains, well, thin.
  • Bettis is the only Big Back to crack the Top 50 in all-time rushing yards. He stands at No. 5.
  • Just 3 of the 10 most productive Big Backs of all time averaged more than 4.0 YPC for their career.
  • 1 of those 3, Cookie Gilchrist, played his entire career in the AFL.
  • The 10 most productive Big Backs of all-time combined to average just 4.0 yards per carry.
  • Big Backs are one-dimensional. The 10 most productive Big Backs of all-time have combined to catch a mere 38 TD passes.
  • Tampa star Big Back Mike Alstott accounts for more than one-third of those TD receptions (13).
Put most simply, big guys are not meant to carry the ball in the NFL. Sure, it sounds great to think that your team has a 250-pound guy crashing into opposing defenses. But when that defensive front wall is filled by linemen who each chime in at over 300 pounds, it's a losing battle for the ballcarrier.
The solution, of course, is to slip past and run around the defenders – something smaller, more elusive ballcarriers can obviously do better. 
To prove the general superiority of smaller backs, we created something called Yards Per Pound. It measures how many yards a back generated over the course of their career for every pound of body weight. The top of the food chain includes all-time leading rusher Emmitt Smith and the man he replaced at the top, Walter Payton.
  • Smith (212 pounds, 18,335 rushing yards) generated 86.5 Yards Per Pound
  • Payton (200 pounds, 16,726 rushing yards) generated 83.6 Yards Per Pound
Even the most productive Big Backs of all time, the players most likely to be described by the "pundits" as "tough" and "durable," simply do not come close. Only the Top 5 generated more than 20 Yards Per Pound. Only Bettis generated more than 30 Yards Per Pound. However, Baltimore's 240-pound Jamal Lewis, who currently stands as the second most productive Big Back in history (6,669 rushing yards), has an outside opportunity to exceed Bettis as the best.
Here's a look at the 10 most productive Big Backs in NFL history. Each weighed at least 240 pounds. You'll find that, pound for pound, elite Big Backs are rarely as productive or as durable as smaller, more elusive players.