The team's most likely decisions were (as noted by
@rabidfireweasel and
@Ring 6):
1. They didn't want to release someone who would have to go through waivers, so they released vets with 4 years who were automatically FAs.The vets most likely agreed to the release and agreed to return.
2. They didn't pay an extra $500k, they only paid the $500k early which was nice because the player was being loyal to the team by being released and promising to return.
3. There are only 8 total season IR/NFIs (designated to return). The preseason allows 2 IR/NFIs, but those preseason designations count towards the 8 total. So the team did not want to use a preseason IR/NFI if they didn't have to because they want to save their IR designations in case they need them later.
Got it?