The precedent has been set by Willie Murrell and Mitch Richmond that you don't have to be a four year player. And Beas undoubtedly had the single greatest season for any KSU player ever. He needs to go up.
But the precedent has also been set by the estroballer (think it was Lehning) that we can retire jerseys while the player is still active. Mike Evans, Lon Kruger, Chuckie Willams...there's no way to argue that Jake doesn't belong with that group.
As for Cartier, how could you not also add Askia Jones? I could probably think of a few others. Cartier was great, but this is the elite of the elite.