It was certainly a scary moment when San Francisco 49ers backup defensive lineman Tarron Jackson needed to be carted off the field during training camp practices, and head coach Kyle Shanahan was mindful of a potentially serious neck injury despite positive responses from the defender.
Jackson, a roster hopeful, might take a while to get back onto the field, meaning Shanahan and coordinator Robert Saleh were probably convinced the team needed a move to bolster the defensive line's depth chart.
The Niners already were on the hunt for a D-lineman, working out several players during camp and one lineman in particular, Jaylon Allen, formerly of the UFL Memphis Showboats.
The workout took place the day before Jackson's injury, so San Francisco was already intrigued by the 6-foot-2 and 245-pound Allen, who went undrafted out of Memphis in 2024 and briefly spent time with the Denver Broncos that year before being waived as injured.
Now, though, Allen's addition seems to have been fully triggered by Jackson's injury.
On Tuesday, NFL Network's Ian Rapoport confirmed Allen signed with the 49ers:
The #49ers are signing DE Jaylon Allen this morning, source said, as the former edge with the UFL’s Memphis Showboats gets a shot.
— Ian Rapoport (@RapSheet) July 29, 2025
While the nature of the deal isn't known, it likely carries zero in guaranteed money, meaning Allen will have a chance to round out the back end of the D-line depth chart, leading to some potential snaps late in games this preseason.
However, with a number of well-established names above him at defensive end, including Nick Bosa, Bryce Huff, Mykel Williams and Yetur Gross-Matos, it'll be a hefty challenge for Allen to have a serious chance.
Allen managed 23 tackles, 1.5 sacks and a forced fumble over 10 games with the Showboats last spring, so he's hoping he can translate that solid performance over into an NFL-caliber effort. The defender also managed 13 sacks over five collegiate seasons, too.
He's still a long shot, but Jackson's injury could pave the way to an increased chance of hanging around.