Prior to the first cutdown date in training camp, injured players with fewer than four years of service time cannot be placed on injured reserve until they pass through waivers. Teams will cut this sort of player with a waived-injured designation, allowing other teams to place a claim if they so choose. If the player goes unclaimed, his team can place him on IR or agree to an injury settlement, then fully release him from the roster. https://www.profootballrumors.com/2019/06/nfl-waivers-difference-release In order for Bolton to be eligible to return from injured reserve this year, he has to be waived/injured before he can be placed on revocable IR. If they placed him on IR before the cuts, like ESB, he would be ineligible to return from IR this year. Also, if he clears waivers and is released, I believe they can resign him to the active roster without having to spend a minimum of 8 weeks on IR. So this may be a play to try to get him back before the end of the year.