I think much of it is borne out of Bama's trouble with Deshaun Watson, a historically good college QB.
But once you look at the QBs Kirby has beaten since 2017, there doesn't seem to be much 'struggling' from the rushing side of it - granted, not all of these are considered good to great QBs, but they are/were all 'dual threat:'
Brandon Wimbush, ND
Nick Fitzgerald, Miss St
Feleipe Franks/Malik Zaire, UF and Ark
TaQuon Marshall, GT
Baker Mayfield, OU (12 carries, 1 yard)
Jalen Hurts, Bama (zero points, benched at halftime of natty)
Terry Wilson Jr, UK (12 carries, 12 yards)
Ian Book, ND
Bo Nix, AU and Oregon x 1,000,000
Charlie Brewer, Baylor (9 carries, 7 yards)
KJ Jefferson, Arkansas
Joey Gatewood, UK
Luke Doty, SC
Connor Bazelak, Mizzou
Desmond Ridder, Cincy (15 carries, -17 yards)
Emory Jones, UF
Brady Cook, Mizzou
Hendon Hooker, UT x 2
JJ McCarthy, Michigan
Bryce Young (natty)
Anthony Richardson, UF
Max Duggan, TCU
Jaxson Dart, Ole Miss
Arch Manning, Texas
dual threat QBs who murdered us:
Joe Burrow
Sam Ehlinger (3 rushing TDs, we were disinterested)
Bryce Young (SECCG)
Jalen Milroe
But once you look at the QBs Kirby has beaten since 2017, there doesn't seem to be much 'struggling' from the rushing side of it - granted, not all of these are considered good to great QBs, but they are/were all 'dual threat:'
Brandon Wimbush, ND
Nick Fitzgerald, Miss St
Feleipe Franks/Malik Zaire, UF and Ark
TaQuon Marshall, GT
Baker Mayfield, OU (12 carries, 1 yard)
Jalen Hurts, Bama (zero points, benched at halftime of natty)
Terry Wilson Jr, UK (12 carries, 12 yards)
Ian Book, ND
Bo Nix, AU and Oregon x 1,000,000
Charlie Brewer, Baylor (9 carries, 7 yards)
KJ Jefferson, Arkansas
Joey Gatewood, UK
Luke Doty, SC
Connor Bazelak, Mizzou
Desmond Ridder, Cincy (15 carries, -17 yards)
Emory Jones, UF
Brady Cook, Mizzou
Hendon Hooker, UT x 2
JJ McCarthy, Michigan
Bryce Young (natty)
Anthony Richardson, UF
Max Duggan, TCU
Jaxson Dart, Ole Miss
Arch Manning, Texas
dual threat QBs who murdered us:
Joe Burrow
Sam Ehlinger (3 rushing TDs, we were disinterested)
Bryce Young (SECCG)
Jalen Milroe