My assumption was that these were all hosts of current programming on the channel.
I think it's simpler than that: all of them, at some point, hosted a game show that's owned by Fremantle*. That's why Pat Sajak is an interesting inclusion for me, since as far as I know the only game show of his that falls under the Fremantle umbrella is the unsold
Puzzlers.
I think the only host in the bracket who hasn't appeared on Buzzr programming yet is Barker: Sajak was on the debut week of
Super Password, IIRC Eubanks has only appeared by way of some
Trivia Trap clips Buzzr used in their Pick & Play Sweepstakes promos back in October, and everybody else either has a series currently on the schedule or one Buzzr pulled out for special programming (Joe Garagiola with
He Said She Said, Allen Ludden with
Password/
Password Plus, Ray Combs with his era of
Family Feud, and Jack Narz with
Now You See It).
(*Or, heck, if you wanted to limit it further: all of them hosted a game show for Mark Goodson.)