On Thursday night, we'll see the third game of a burgeoning rivalry between two of the most talented young quarterbacks in football. Justin Herbert made an unexpected debut in Week 2 against Patrick Mahomes and the Chiefs last season, taking over the Chargers' starting job with no advance notice after Tyrod Taylor's lung was punctured by the team doctor before the game. Herbert gave a good accounting of himself in a narrow 23-20 loss, but while the Chiefs pulled this one out in 2020, Herbert & Co. roared back with a 30-24 victory in Week 3 this season.
More than any other combination of young quarterbacks in the league at the moment, this feels like it has the chance to turn into a classic rivalry in the years to come. All of the criteria you would look for are there. These are two of the best signal-callers, playing for successful teams, in a division in which they'll get to face off twice per season. Mahomes might end up getting pitted against guys such as Josh Allen and Lamar Jackson, but until the Broncos and Raiders land on someone as good as Herbert, this is going to be his closest rivalry.
Of course, what seems like a classic rivalry early in a pair of young careers doesn't always go that way. It looked like Carson Wentz and Dak Prescott were going to play each other for a decade, but that ended when Wentz was dealt to the Colts earlier this season. Andrew Luck and Marcus Mariota were No. 1 overall picks playing each other in the AFC South, but neither is there any longer. Jay Cutler and Philip Rivers seemed like a perfect match of antagonists, but Cutler was traded away by former Broncos coach Josh McDaniels after three seasons. The Brett Favre-Steve Young-Troy Aikman triangle match in the early 1990s didn't see one another often enough. You get the idea.
As I thought about it more, I realized that I needed to take a step backward. What actually qualifies as a significant, long-term rivalry in the NFL? How many times do two quarterbacks have to play each other before it stands out as historically significant? And is there a rivalry from history that might look like what we'll hope to see from Mahomes and Herbert in the years to come?
To answer these questions, I looked at every quarterback matchup since 1970 in which the starter threw at least two passes. I tracked each passer's record against every other starter he faced over the course of their respective careers. There have been a total of 12 quarterback rivalries over that timeframe in which two passers matched up against each other at least 16 times. Let's run through those 12 matchups and what happened over the course of their rivalries. There are two quarterbacks who appear more than once on the list, and I would be surprised if you could guess either of them without cheating. I certainly couldn't.