There's turnover in the NFL every year. For the Indianapolis Colts, turnover has been the norm, rather than the exception, over the last three years.
This offseason has been no different. The team projects to have at least three, maybe four new offensive starters, as well as shifted responsibilities on the offensive line for several players. On defense, the same story applies, with at least three new starters and a few other possibilities.
That happens when you allow veterans like Reggie Wayne and Cory Redding to leave in free agency. Replacements have to come from somewhere.