Ian Rapoport of NFL Network reported the roster move and noted the Raiders now get to keep their seventh-round pick in the 2019 NFL draft, which was conditionally sent to New York in the deal.
Hackenberg always seemed like a reach when the Jets selected him in the second round of the 2016 draft.
The 23-year-old Penn State product struggled across his final two years with the Nittany Lions after a solid freshman campaign. In all, he completed just 56.1 percent of his throws with 48 touchdowns and 31 interceptions across 38 games at the collegiate level.
His accuracy problems persisted with the Jets. He only connected on 59 of his 121 attempts (48.8 percent) during six preseason appearances over the last two years. He didn't appear in any regular-season games.
Before the trade, Hackenberg said he was ready for another chance to prove himself after spending the offseason refining his throwing motion.
"It's a really solid foundation for me moving forward, and I'm excited about it," he told reporters. "All I know is I'm 23 and I've got a lot of ball ahead of me. My career hasn't even started yet. I'm excited about what the future holds because I know deep, deep down that this was really big for me."
Raiders head coach Jon Gruden explained the rationale behind the low-risk move last month.
"We're looking for players," he said. "We're looking to get better every day, and Christian Hackenberg was available. He was a second-round pick. He did some really encouraging things at Penn State. He had some ups and downs. We're going to look at him, and we're going to make it very competitive to see who Derek Carr's backup is."
Three weeks later, Oakland decided it'd seen enough to move forward with EJ Manuel and Connor Cook battling for the backup role.
Hackenberg may land with another organization as a training-camp arm, but he'll struggle to make a 53-man roster for the 2018 season.