Witten was likely a Pro Football Hall of Fame inductee as it stood, but he came out of retirement to rejoin the Cowboys. Padding his already impressive statistics likely won’t hurt, but even if he has a bad season in his comeback it isn’t going to hurt him.
The current leader in Touchdown Receptions is a free agent after playing all of his career with the San Diego/Los Angeles Chargers. Gates was very good in his first half and good enough in his second half of his career. If he can latch on with another team and get to 12,000 Yards it wouldn’t hurt, but this is a position that is hard pressed to see inductees.
The retirement of Rob Gronkowski ensures that right now that Travis Kelce has to be considered the best Tight End in Football. Kelce is well over the AV/G for his position, but Tight Ends really need to compile stats in this era.