While both may be a nice veteran fit for the Jaguars, I think Bly would bring the most to this team because of McAlister's recent injury problems. Bly could sign to a one or two year contract for a much smaller amount than what the Broncos were paying him.
McAlister would also be a nice fit for the Jaguars, whose secondary last year was very disappointing. The complete flop known as Drayton Florence, and the inconsistent play of Brian Williams would definitely benefit this year by the signing of Bly or McAlister.
Some younger and larger names may hit the market, like the Texans' Dunta Robinson, but would cost far too much for the Jaguars to pursue.
Hopefully the Jaguars will go after one of these two veterans, and we may see a couple more releases soon as teams cut more players each day.