Is KY vs FL really worth the 3:30 CBS slot?
Because of its contract, CBS only starts to get first selection of SEC games in week 3 (it used to be because they had the rights to broadcast the US Open, which ESPN has since purchased...note the lack of ESPN2 games in week 1).
Before then, CBS can purchase the broadcasting rights to a game from ESPN that ESPN's willing to sell to them...so essentially they've got the 2nd or 3rd pick during those first two weeks.
Broadcasting rights also relate to who's the home team.
If you look at the slot of games involving SEC home games in week 2:
Nicholls State at Georgia
Prarie View A&M at Texas A&M
Kentucky at Florida
Western Kentucky at Alabama
Middle Tennessee at Vanderbilt
Wofford at Ole Miss
South Carolina at Mississippi State
Arkansas State at Auburn
Jacksonville State at LSU
Eastern Michigan at Missouri
There really aren't a lot of great options, and since ESPN gets first choice for the first two weeks, it likely used that on the South Carolina vs Mississippi State game.
For ratings purposes, CBS is always going to take an SEC vs another SEC team (or at least versus another FBS team) when it's possible, as opposed to an SEC team playing a mid-major or FCS team.
With that week 2 lineup, that pretty much only left Kentucky vs Florida for CBS to purchase.