The Atlanta Falcons could be facing a significant setback on defense after linebacker Jalon Walker suffered what appeared to be a serious injury during training camp practice.Atlanta Falcons linebacker Jalon Walker suffered what appeared to be a serious injury during training camp practice. (IMAGN IMAGES via Reuters Connect)What happened to Jalon Walker?The 2025 first-round pick was carted off the field after going down, with teammates gathering around him before he was taken away. Practice was brought to an early end shortly afterward.Reporters in attendance indicated Walker appeared to injure his left leg, with several teammates taking a knee as medical staff assisted him onto the cart.ESPN and NFL Media insider Ian Rapoport, along with NFL Media reporter Steve Wyche, later reported that Walker is "feared to have torn his ACL." The Falcons have not yet released an official update on his condition.Head coach Kevin Stefanski addressed the team before calling an early end to the session. The practice session was called off roughly 45 minutes ahead of schedule following the injury.Falcons face defensive setbackWalker’s injury could create additional challenges for Atlanta, especially with fellow 2025 first-round selection James Pearce Jr. dealing with ongoing legal matters and the possibility of an NFL suspension. Pearce Jr. led the Falcons with 10.5 sacks last season.Also read: Coby Bryant injury update: What happened to Bears safety before being carted off at training camp?Walker, meanwhile, emerged as one of the bright spots on Atlanta's defense during his rookie campaign. He finished the 2025 season with 36 tackles, 5.5 sacks, two forced fumbles and one fumble recovery.He also generated 29 total pressures on 282 pass-rush snaps, while Pro Football Focus gave him an 81.3 run-defense grade, highlighting his impact against the run.Why Walker was crucialThe 22-year-old had been viewed as one of the Falcons' most valuable defensive pieces heading into the 2026 season, making his potential injury especially concerning.The second-year defender was widely projected as a breakout candidate after an encouraging rookie campaign and was expected to shoulder a significantly larger workload.Also read: Aaron Rodgers vs ESPN: Steelers QB questions network's coverage of Russini-Vrabel scandal; 'Nobody can talk about it'Atlanta also planned to expand his responsibilities by taking advantage of his versatility. In addition to rushing off the edge, the coaching staff intended to use Walker more frequently at his natural college position of inside linebacker.The idea was for him to help fill the void left by Kaden Elliss while serving as a multipurpose weapon in defensive coordinator Jeff Ulbrich's scheme.