The Patriots took a flier on undrafted free agent offensive tackle R.J. Mattes in the hopes that he could develop into a respectable back-up swing tackle. Standing at 6'6, 315 lbs, Mattes certainly had the size for the position and as a four year starter at NC State, he had the experience.
Mattes yo-yo'd on the roster during the off-season before settling in during pre-season, earning playing time as the right tackle with the second line and left tackle when Will Svitek sat down. Mattes looked like the best second stringer on the field and had a chance to make the practice squad, if not push for a final roster spot, before he went down with an ankle injury against the Buccaneers in week 2 of the pre-season.
The Patriots released him and he made it through waivers and on to the Injured Reserve list. The Patriots were able to clear him off the list with an injury settlement.
Now, the league suspended Mattes four games, which likely correlates with the "performance enhancing drugs" offense.
There's no way he'll be back with the Patriots at this point, especially as fellow injured UDFA tackle Brice Schwab sits on the injured reserve.