Free agency and the NFL draft bring roster changes to every team in the NFL, including the Jacksonville Jaguars. It's never easy to tell exactly who will start and won't, but that's part of the NFL and part of the fun.
The Jaguars might have a new set of starters going into the 2015 season, thanks to free agency and the draft. The team has picked up some very valuable players to help the team succeed, and I would expect most of them to start sooner rather than later.
With a team as young and developing as the Jaguars, the change in starters should be expected.