It looks like many of the RB unsigned at this time are older. I looked up a couple of the younger backs on your list. The players who are not older seem to have an injury history (D'Onta Foreman -Achilles and Duke Johnson -Neck). Ito Smith might be neither old or injured but he has not been very productive.
[
en.wikipedia.org]
Ito Smith was a 4th round selection (pick 126) by the Falcons in 2018. He took snaps away from Gurley at the end of last season as "Raheem Morris wanting to give Smith a good look." Smith averaged more yards per carry than Gurley at 4.3 YPC. He is 25 and in his 3 NFL seasons has never rushed for more the 300 yards in a season. (689 rushing and 314 receiving in 3 seasons). He had a concussion his second season.
Height 5 ft 8+5⁄8 in Weight 200 lb 40-yard dash 4.45 s 10-yard split 1.57 s 20-yard split 2.58 s 20-yard shuttle 4.56 s Three-cone drill 7.22 s Vertical jump 36+1⁄2 in Broad jump 9 ft 11 in Bench press 22 reps
_________________________________________________________________________________________________________________________
D'Onta Foreman was selected by the Houston Texans in the 2017 NFL draft in round 3 (pick 89)
Height 6 ft 0+1⁄4 in Weight 233 lb Arm length 31+3⁄8 Hand size 10+1⁄8 40-yard dash 4.46 s 10-yard split 1.63 s 20-yard split 2.57 s 20-yard shuttle 4.29 s Three-cone drill 7.21 s Vertical jump 33 in Broad jump 10 ft 0 in Bench press 18 reps
He is a good sized RB who ran a fast 40. He rushed for more than 2000 yards in 2016 at the university of Texas. Foreman had 300 yards rushing as a rookie and tore his Achilles. He never had more than 100 yards in a season after his rookie year.
