With left tackle Anthony Castonzo announcing his retirement, the Indianapolis Colts have a hole to fill next to All-Pro left guard Quenton Nelson. Both Castonzo and Nelson have been cornerstones for one of the league’s best offensive lines over the last three years, and Nelson is so good that the Colts are contemplating moving him to left tackle to fill the void left by Castonzo.
It’s not a crazy thought. When Nelson came out of college, we debated the merits of moving him to tackle to tap into his unique skill set at a more valuable position. The debate centered around the value of an average to good offensive tackle versus an elite guard. We debated this under the assumption that Nelson was destined to become one of the league’s best guards, but it was difficult to project him as anything more than an average to above average offensive tackle.
Three years later, Nelson has been by far the most valuable guard in the league. In fact, he’s been the most valuable offensive lineman altogether. The Colts are posing the same question about his value on the interior versus the most important position along the offensive line: left tackle.
Given the state of NFL offensive tackle play, our intuition has been that average to good offensive tackle play should outweigh the value of elite guard play. But what do the numbers say?