The Oakland Raiders have released Christian Hackenberg.

The Raiders acquired Hackenberg three weeks ago for a conditional seventh rounder in 2019.

Jon Gruden said the decision was made to cut Hackenberg because roster spots were needed to sign veteran defensive linemen Frostee Rucker and Ahtyba Rubin.

"I was disappointed in not really giving Christian the opportunity to go to camp," Gruden said after practice Tuesday. "We felt like we needed to add a couple defensive linemen. We ran out of numbers, and that's not good at that position heading into camp."

Gruden was previously known as being high on Hackenberg.