Are you serious here? No one signs a 5-star at every position every year - let alone two. I mean not even Saban does that (he's signed TWO 5-star CBs in the last SIX signing classes, and none committed or leaning for next year).
That being said, look who Kirby has brought in - and continues to bring in. Last year, he signed the top CB in the country in Kelee Ringo. He sat out 2020 rehabbing an injury. This year we signed the top CB in Georgia Nyland Green. For next year we've gotten a commit from 4-star in state CB Marquis Groves-Killebrew, and are in good shape for the top CB in Alabama Trequon Fegans, and 5-star Athlete Malaki Starks from Jefferson Ga, who projects as a DB and is set to announce his commitment in a couple weeks.

But 24/7 rankings aren't the whole story. Kirby signed Eric Stokes as a 3-star recruit and developed him into a likely 1st/2nd round draft pick.

Yes, CB is one of the few question marks going into 2021, but it's comical to even try to criticize Kirby's recruiting or development at the position.