The biggest story heading into Week 3 of the regular season is the meteoric rise of two very different quarterbacks: the 23-year-old Patrick Mahomes and the 35-year-old Ryan Fitzpatrick. Together, they have posted 18 touchdowns to just one interception through four combined games, numbers that are unprecedented in the modern era.

Adjusted Yards per Attempt (AY/A) is a passing efficiency metric that treats touchdown passes as a gain of 20 yards, interceptions thrown as a loss of 45 yards and is highly correlated with winning football games. When we think of post-merger eras, we should probably think about three time periods:

1970-1977: an era in which pass blockers were unable to use their hands and defensive pass interference was not strictly enforced. 1978-2003: an era in which pass blockers were able to use their hands but defensive pass interference was not strictly enforced. 2004-Present: an era in which pass blockers are able to use their hands and defensive pass interference is strictly enforced.

When you look at AY/A by the year, it is very apparent that these are the three significant splits in passing efficiency over the last five-ish decades, all of which are defined by rule changes. Even in this 2004-Present era in which the modern passing boom has exploded both efficiency numbers and volume numbers, we have never seen anything like what both Fitzpatrick and Mahomes have done. At the moment, Fitzpatrick’s AY/A sits at 15.3 with Mahomes at 14.2. Among passers with at least 40 passes through the second week of the season, Fitzpatrick’s AY/A ranks second all-time behind 1971 Joe Namath. Mahomes is fifth on the all-time list through two weeks with 1984 Phil Simms and 1983 Lynn Dickey above him as well.

To find modern comparisons for what we might see from Fitzpatrick or Mahomes later on this season, as their current pace seems unstable to even the naked eye, I took a look at what hot starts in today’s NFL (2004-Present) translate to. Below are the 20 best AY/A marks since 2004 (minimum 40 passes) in the first two weeks of the season.

The difference between the third-ranked quarterback on this list and the 20th-ranked quarterback on this list (what amounts to one yard per pass) is 3.5 times the difference between Fitzpatrick and the best quarterback start from 2004 to 2017 (2008 Kurt Warner.) Finding an exact fit for Fitzpatrick and Mahome is impossible because the only people to come close to what they have done played in an era with completely different, game-changing rules. With that being said, it is always useful to look at the most similar comparisons to forecast someone’s season moving forward. This is why I tracked what these 18 quarterbacks from 2004 to 2017 did after their “hot start” to their season.

Out of the 18 quarterbacks, two of them had losing records, two of them went .500 and 14 of them had winning records following their fast start to the season. It should be noted three of the four quarterbacks who went .500 or less (2013 Michael Vick, 2015 Marcus Mariota and 2004 Donovan McNabb) only played 21 games combined (out of a possible 42 games) due to injury. For the most part, healthy passers coming off of a hot start continue to win football games, even if their numbers start to slip. The average quarterback on this list went 8.2-3.7 after Week 2, notable in a league where a 10-6 record usually gets you in the playoffs.

Despite their records, not one of these 18 quarterbacks was able to sustain his Week 1-2 pace for the remainder of the regular season, but that did not mean that they fell off the face of the Earth either. Only four of them (2006 Rex Grossman, 2013 Michael Vick, 2010 Jay Cutler and 2015 Marcus Mariota) had a Week 3-Week 17 AY/A under 7.0, basically the league average mark in the NFL right now. It might be worth noting that Mariota is the only passer on this list (other than 2018 Mahomes) who is under the age of 26.

On average, quarterbacks with fast starts finished the season with 23.7 touchdowns, 9.6 interceptions and an AY/A of 7.9 after Week 2. To put that into perspective, an AY/A of 7.9 would have ranked in the top quarter of passers in 2017. The numbers would suggest that Mahomes and Fitzpatrick are likely to be top-10ish quarterbacks from this point forward. This becomes an interesting factor in Tampa Bay’s season, as by far the biggest underdogs to win the NFC South have now established themselves at 2-0 with a quarterback replacing their suspended former first overall pick Jameis Winston.

Fitzpatrick has only one more game (vs Pittsburgh) to prove himself before Winston is eligible to return to the team. After the Monday Night Football game against the Steelers, the Buccaneers have to travel to Chicago to face the Bears on a short week before their bye week. There is not an easy time for Winston to re-enter the lineup with the way their current schedule is slated, at least until their adjustment-filled bye. If he is not the starting coming out of the bye, it just may not happen in 2018.

If Tampa Bay takes a close look at the performance trends of quarterbacks who get off to a fast start in this era of football, they might just elect to roll with their “backup” as their full-time starter. Eight (or more) wins moving forward likely gets the Buccaneers into the playoffs, somewhere head coach Dirk Koetter has never been before as the shot-caller.

While it is easy to point to young quarterbacks immediately succeeding at their first shot in a starting role, be it Mahomes, Russell Wilson, Aaron Rodgers, Ben Roethlisberger or Philip Rivers, it is much harder to find a long-term comparison for a late-breakout like Fitzpatrick turning into a quality full-time starter. The most successful quarterback in this role is probably Rich Gannon, who from 1987 to 1998 had an AY/A of 5.7 but had an elite stretch of play from 1999 to 2002 (AY/A: 7.4) To put those numbers into perspective, an AY/A of 5.7 would have ranked 32 out of 43 qualifying passers from 1999 to 2002. 7.4, the number Gannon turned around to, ranked second.

Clearly, we are in some uncharted territory. Still, quarterback performances that are even within an arm’s reach of what Mahomes and Fitzpatrick have done over the last 15 years leave us to believe that they will continue to be top-quarter quarterbacks moving forward. Hang along for the ride. This could be a weird one.