Until I see differently, I'm sure that the Tre White contract will not make him a "lock".
Beane will draft a CB that in both his and McDermott's minds will hopefully be starting sometime during the year.
I have Johnson, Benford and the Rookie (1st - 4th round) as locks.
At least one of Lewis/Jackson will no doubt make the 53.
It's going to be a battle for the other 2 CB slots.
The secondary is going through a big change, and I bet they will wait and see who plays best together.