Only a few rookie “quarterbacks” have ever led a team to an NFL title, with quarterbacks in quotation marks the farther back in time we go. In 1946, a 25-year-old Otto Graham led the Cleveland Browns to an AAFC title in his first season. The prior year, a 25-year-old Bob Waterfield led the NFL in touchdown passes as a rookie and then threw two touchdown passes in the NFL title game to help lead the Rams to their first ring. Perhaps the best rookie season of them all came from Sammy Baugh in 1937, as he led Washington to the championship. And three years earlier, rookie Ed Danowski helped the Giants stage a fourth quarter comeback to beat the Bears in a famous title game.

Purdy has only started five regular season and two playoff games in his NFL career so far, and he sports a perfect 7-0 record. An appearance in Super Bowl LVII would be his 9th NFL start; believe it or not, that would only rank as the third fewest by a starting quarterback in the Super Bowl. On the other hand, at just over 23 years old, Purdy would in fact be the youngest quarterback to start a Super Bowl.

The table below shows every quarterback to start a Super Bowl, along with the final four quarterbacks remaining in the 2022 playoffs. Purdy would replace Dan Marino as the youngest quarterback to ever start the Super Bowl, and would be starting the big game one game earlier than fellow 49ers quarterback Colin Kaepernick.

Purdy isn’t the only player looking to make history.

• Patrick Mahomes led the NFL in passing yards this season, and no player has ever done that and won the Super Bowl in the same season. Johnny Unitas, in 1959, was the last quarterback to lead the NFL in passing yards and win a ring in the same season. Mahomes, who will win the AP (and likely every other organization’s) Most Valuable Player Award, is also trying to break a weird curse. No quarterback since Kurt Warner in 1999 has won the AP MVP award and a Super Bowl in the same season, a remarkable span of over two decades. Since 2000, quarterbacks to appear in the Super Bowl in the season they won the AP MVP award are 0-8 in the big game (Warner ’01, Rich Gannon ’02, Tom Brady ’07 and ’17, Peyton Manning ’09 and ’13, Cam Newton ’15, and Matt Ryan ’16).
• Joe Burrow is trying to become just the third quarterback to start and win a Super Bowl after leading his college team to a national championship. The first two have something else in common: Joe Namath and Joe Montana.
• Jalen Hurts is also pretty young and inexperienced: he’d be the second-youngest NFC quarterback to start a Super Bowl. If the Eagles win it all, Hurts would shatter any remaining questions about dual-threat quarterbacks. As it stands, Russell Wilson’s 33.7 yards per the game remains the highest rushing average by any quarterback in a season they won the Super Bowl (Wilson averaged 53 yards per game the year the Seahawks lost); during the regular season, Hurts averaged 50.7 rushing yards per game and ran for 13 touchdowns. The record for rushing yards in a Super Bowl by the winning quarterback is 59, set by Joe Montana back in Super Bowl XIX. That is another mark that Hurts could challenge in a couple of weeks.

But the Buccaneers did not have a particularly large amount of turnover compared to recent Super Bowl champions. In fact, by one measure, each of the five previous Super Bowl champions had bigger turnover than Tampa Bay. Other than Brady, most of the big names didn’t have a big impact for Tampa Bay, at least until the Super Bowl. Leonard Fournette had just 367 rushing yards during the regular season; Brown had just 483 receiving yards in 8 games; Gronk averaged 39 yards per game, the lowest mark in his career other than during his rookie season (in ’19, O.J. Howard averaged 33 yards per game for Tampa Bay). Of course, in Super Bowl LV it was a different story: our lasting image of the 2020 Bucs will be Gronkowski scoring 2 touchdowns, Brown catching a touchdown, and Fournette picking up 135 total yards and a touchdown.

How do we compare one team to its squad from the prior year? Great question! It’s tricky: we want to compare not just roster turnover, but the value of those players. The Chiefs added both Brady and LeSean McCoy, but that should not count as equal moves. Similarly, you have to look at how the player was used in the prior season. For example, Kurt Warner was on both the ’98 Rams and the ’99 Rams, but it would be poor analysis to say that the ’99 Rams had the same quarterback as they did the prior year.

Really we want to look at two things: how much was the player a part of the Super Bowl team (to avoid overemphasizing the McCoys of the world) and for players on the team, how much was that player a part of the team the prior year (to avoid the Warner problem). To measure how valuable a player was, I am going to use PFR’s AV, which does as good a job as any other metric to compare the value of players across positions and eras. For each player on each Super Bowl team, I will measure how much AV they produced as a percentage of the team’s total AV. I will also do that the year before, and then take the lower of those two values.

Let’s use a few examples. The 2020 Buccaneers had 243 points of AV, and Brady had 15 of them; therefore, he was responsible for about 6% of the team’s value. He was not on the team in 2019, of course, so Brady gets a 0 when we calculate how much of the 2019 Bucs were on the 2020 Bucs. That’s a big deal, because there is only 94% of the AV left to allocate. McCoy had just 1 point of AV, or 0.4% of the team’s AV; he also gets a zero since he wasn’t on Tampa Bay in 2019, but that has a much smaller impact. Donovan Smith had about 4% of the AV on the 2019 Bucs and 4% of the AV on the 2020 Bucs; therefore, taking the minimum doesn’t change things; he gets assigned 4%.

If we do this for every player on the 2020 roster, and take the minimum value between the percentage of AV they had for the ’20 Bucs and the percentage of AV they had for the ’19 Bucs, and then sum the results, we get a value of 60%. This may not mean a ton to you in the abstract — it wouldn’t be quite right to say that 40% of the roster turned over — but it is very helpful if we are comparing teams.

The 2020 Buccaneers had 13 players with at least 8 points of AV; Brady and Wirfs were the only players who weren’t on the team in 2019. By comparison the 2019 Chiefs had 14 players with at least 7 points of AV; four of them (Tyrann Mathieu, Frank Clark, Damien Wilson, and Bashaud Breeland) weren’t on the 2018 team, and that doesn’t even include two starting lineman (Austin Reiter and Laurent Duvernay-Tardif) who went from backups to starters. By this methodology, the ’19 Chiefs had about 54% of the same roster in 2019 and 2020, a bit lower than Tampa Bay.

In the free agency era, there is bound to be more turnover year to year. The ’91 and ’92 Cowboys were about 75% “the same” using this methodology; no Super Bowl team has matched that mark since. A few Super Bowl champions — the ’66 Packers, ’69 Chiefs, ’73 Dolphins, ’75 Steelers, and ’79 Steelers — have come close to the 80% mark. And three teams have been below 50%: the 1980 Raiders, the 1999 Rams, and the 2001 Patriots.

Here is the full data for each player on each Super Bowl team. Here’s how to read the top line. In 2019, the Chiefs won the Super Bowl, and Mahomes was the team’s top player by AV. In the Super Bowl year, Mahomes was responsible for 7% of the team’s AV; the year before, he was responsible for 9% of Kansas City’s AV, so he goes down as 7%. If you do that for every player on the 2019 Chiefs, you get a total of 54.3%, which is shown in the final column.