That was only the most recent change.
I did not say all changes had been made in the 90s, just most were and they were more significant.
https://slate.com/culture/2014/09/1...ribund-league-and-created-the-modern-nfl.html
I think the change in 05’ had a bigger impact but agree some changes in the 90’s also helped.
Just a couple stats to consider.
The avg of the top 9 passers each year and note the increase of 4K QBs
92’ - 3431, 1 4K QB.
93’ - 3473, 2 4K QB.
94’ - (the article you provided had big changes) 3948, 3 4K QB.
95’ - 4043, 4 4K QB.
96’ - (increased enforcement on 5 yard contact rule) 3690, 3 4K QB
97’ - 3625, 0 4K QB
98’ - 3709, 2 4K QB. I think this was the plateau mark for the 90’s changes until 05’.
99’ - 3953, 5 4K QB
00’ - 3924, 3 4K qb
01’ - 3920, 2 4K qb
02’ - 3984, 4 4K qb
03’ - 3782, 2 4K qb
04’ - 4175, 5 4K qb
05’ - 3813, 2 4K qb, Peyton manning rule instituted.
06’ - 3958, 5 4K qb after 1 year of adjustment, the 4K qb jumps
07’ - 4176, 7 4K qb
08’ - 4165, 6 4K, 1 5K qb
09’ - 4417, 10 4K qb
10’ - 4100, 5 4K qb
11’ - 4709, 10 4K, 3 5K qb
12’ - 4665, 11 4K, 1 5K qb
13’ - 4605, 9 4K, 2 5K qb
14’ - 4602, 11 4K qb
15’ - 4558, 12 4K qb
16’ - 13 4K qb
17’ - 8 4K qb
18’ - 12 4K qb
So 93/94 saw over a 500 yard increase among the top QBs but really stopped below the explosion of the 4K QBs in 2007. Now we’re reaching 1/3 of the league breaking 4K yards and in some cases the average of the top QBs is almost another 600 yard increase.