2) Randy Gregory isn't a must-keep on the 49ers defensive line
The trade with the Denver Broncos early this season that brought Randy Gregory to San Francisco was supposed to give the team someone who could get to the quarterback and draw attention away from Nick Bosa, but whatever goals John Lynch had in mind when he made that move, they weren't met.
In 12 games with the Niners, Gregory recorded only 2.5 sacks and 11 tackles, and to be honest, he's never been very productive in his career. The former Cowboy reached his career-high sack total of 6.0 on two separate occasions, but other than that his sack totals for the year are 0.0, 1.0, 3.5, and 2.0 (with 3.5 combined between Denver and San Fran this year).
Gregory made $14 million this year, so if you're doing the math at home, that's $4 million per sack. That kind of return on investment just doesn't work, especially for a team like the Niners that has been so smart with its moves.
Trading for Gregory was a low-risk move for the Niners. The Broncos paid the majority of Gregory's salary this year, and the Niners were only on the hook for the veteran's minimum after swapping a sixth-round pick for Gregory and a seventh-rounder. Undoubtedly, Gregory's next contract won't be anywhere near the five year, $70 million deal he got last time he reached free agency, but whatever the number is, his production doesn't justify bringing him back. The Niners gave up practically nothing to get him, so they should treat Gregory as a cheap rental that just didn't work out.