After looking at Hall of Fame baseball player indexes relative to seasonality in recent newsletters and following a request to look at HOF football players, I dug into a subsection of those cards (as there are quite a few more recent HOF football players than HOF baseball players), within a 365-day range: the offseason (Feb. 8, 2025 - Sept. 4, 2025) and the 2025 NFL season (Sept. 4, 2025 - Feb. 8, 2026).

2/8/25-9/4/25 - Biggest Gains

Player Index	Percentage Change
Drew Pearson	174.88
Lee Roy Selmon	111.31
Harry Carson	80.92
Ozzie Newsome	58.32
Dave Casper	48.56

2/8/25-9/4/25 - Biggest Losses

Player Index	Percentage Change
Cliff Branch	-23.26
Cliff Harris	-21.07
Fred Dean	-19.81
Roger Staubach	-19.46
Ken Stabler	-8.79

9/4/25-2/8/26 - Biggest Gains

Player Index	Percentage Change
Lee Roy Selmon	284.96
Ted Hendricks	183.31
Lynn Swann	129.2
Franco Harris	87.98
John Stallworth	51.98

9/4/25-2/8/26 - Biggest Losses

Player Index	Percentage Change
Randy White	-26.27
Ken Stabler	-10.75
Earl Campbell	-8.84
Dan Fouts	-7.06
Joe Greene	-6.64

To see how the rest performed, you can see the full 43-player results here.

Methodology:

The players chosen were all Hall of Famers, had rookie cards between 1970 and 1979, and had Card Ladder player indexes
Each player index was given both date ranges to determine the percentage change in the value of the index
Not all Hall of Fame players have player indexes, as each index has cards Card Ladder determines eligible based on sales activity (more info here), and there is a wide range of the number of cards on indexes (as an example, Jack Youngblood has one card, while Walter Payton has 86)

During the NFL season, 25 of the 33 players with sales data (10 players had no sales data during either period) had either positive or zero percentage changes (the remaining eight having negative percentage changes), while during the offseason, 22 players fell into the same category.

The median (or middle) percentage gain during the season was 10.97%, while during the offseason, the median was a slightly smaller 9.09%.

As a comparison, during the the season itself, the (admittedly modern-heavy) Football index was up 14.7% and the Vintage index was up 12.64%, while during the offseason, the Football index was up 5.23% and the Vintage index was up 7.89%, the Football index showing a pretty obviously seasonality influence.

Improvement-wise, 18 of the 33 players saw their percentage change increase from the offseason to the NFL season, with the largest gain coming from Ted Hendricks’ index (from -8.1% to 183.31%). Meanwhile, the largest fall came from Drew Pearson’s index (from 174.88% to 0%).

The seasonal influence doesn’t appear as obvious as baseball’s, at least for Hall of Famers with rookie cards in the 1970s, players I would assume more current football fans would be more likely to have an affinity for based on (relative) recency bias.

As mentioned previously, you’ll want to do your own research, but there so far appears to be something to seasonality when it comes to vintage sports cards, if to a (expected) lesser extent than modern cards.

Vintage HOF Rookie Card: Ken Riley

In college, Riley was the starting quarterback for the Florida A&M University Rattlers, leading them to three conference titles, only to be converted to cornerback in Cincinnati Bengals training camp by legendary coach Paul Brown.

Ken Riley - DB

HOF Induction in 2023

Standout Stats:

1-time Pro Bowler
Tied for fifth all-time in career interceptions (65) with Charles Woodson
5 or more interceptions in a season seven times
Second-most games played in Cincinnati Bengals team history (207)
Career AV (Approximate Value) - 133

1973 Topps #171

Grade	PSA Pop Count	SGC Pop Count	BVG Pop Count
10	4	0	0
9	48	2	0
8	88	3	2
7	62	5	2

As you can see, there’s a certain consistency with Riley’s rookie card sales at a collector grade, with fewer than $13 separating the highest and lowest sales. Meanwhile, the average price came out to be $105.11.