The Saints signed free agent fullback Heath Evans to a two-year contract on Thursday and released Karney.
"The writing was on the wall for a long time," Karney said. "I didn't play much this year. They wanted to go in a different direction. There's nothing wrong with that. I can still play and play at a high level. I'm confident in that."
Karney, 27, was drafted by New Orleans out of Arizona State in 2004 when Jim Haslett was Saints coach and the offense revolved around a punishing running game led by Deuce McAllister.
Karney and McAllister, released by the Saints last month, became close during the past five years. Karney routinely helped out at McAllister's charity events in the region and was openly emotional about the possibility of parting with McAllister when last season ended, saying, "I'm going to be able to tell my kids someday -- hopefully when I have kids -- that I played with Deuce. I think that says it all right there."
Evans, 30, has played for eight NFL seasons and has carried the ball 157 times for 561 yards and three touchdowns in his career. He has spent the past four seasons with the Patriots, serving primarily as a blocker for the NFL's sixth-best running attack in 2008.
Evans, who visited New Orleans after free agency began last week, was a third-round draft choice out of Auburn by Seattle in 2001 and played four seasons for the Seahawks. He was in Seattle when running back Shaun Alexander set what was then a single-season club record of 1,696 yards rushing.
"Heath is a tireless worker and someone we were very impressed with after spending time with him," Saints coach Sean Payton said. "He's very excited about the various things we do from an offensive perspective and is a well-rounded and versatile player. In addition, he has played quite a bit on various special teams units throughout his career and been a reliable and dependable player in many different situations."
Karney rushed 39 times for 79 yards and five TDs in his five seasons in New Orleans. He also caught 53 passes for 295 yards and two touchdowns. He scored three of his touchdowns in one nationally televised Sunday night game at Dallas in 2006.
"I've been in the league five years and they let me go now, so I get a chance to sign somewhere else," Karney said in a phone conversation with The Associated Press while he was on his way to the rehearsal dinner. "The guy they're bringing in, they think he can do a better job and that's their prerogative. That's their deal and I respect that."