Nick Saban had Jalen Hurts, who had lead Bama to a NCG appearance in 2016(where they lost on a last second TD by a 17th year senior WR), and had guided them back to the NCG in 2017, but Saban opened the second half with Tua when Hurts was struggling. Bama got a natty.
Dabo Swinney had Kelly Bryant, who had lead Clemson to the playoffs in 2017, and was off to an undefeated start in 2018, but the offense wasn't really clicking, so he turned to Trevor Lawrence. Clemson got a natty.
Kirby Smart had Jake Fromm who lead UGA to a NCG in 2017 where they lost on a last second TD, but in 2018 when the offense was stale without Chubb, Michel and Wims, Kirby just stuck with Fromm despite having Justin Fields, Justin Fields transferred to Ohio State and UGA hasn't sniffed a playoff appearance since, much less a natty.