Although the 2013 Baltimore Ravens will have a different look than last season's Super Bowl champions, coach John Harbaugh seems to be taking the changes in stride, telling the NFL Network that it's impossible for a team to stay the same in today's NFL.

"The worst mistake you can make is trying to hold a team together," Harbaugh said in the interview from the NFL's owners meetings in Phoenix, which aired Monday. "It's impossible."

He cited advice he received from the late Bo Schembechler, that "if you try to stay the same you end up getting worse."

This offseason, Baltimore has released safety Bernard Pollard and guard Bobbie Williams, traded wide receiver Anquan Boldin to the San Francisco 49ers, lost linebackers Dannell Ellerbe (Miami Dolphins) and Paul Kruger (Cleveland Browns) and cornerback Cary Williams (Philadelphia Eagles) in free agency, and watched linebacker Ray Lewis and center Matt Birk retire.

Safety Ed Reed remains unsigned and made a free-agent visit to the Houston Texans last week. General manager Ozzie Newsome told USA Today Sports in a story published Sunday that he plans to talk with Reed's representation this week.

Still, Harbaugh said the Ravens' title-winning team will always be together, while the rebooted version will be ready to defend that championship.

"The 2012 world champion Ravens will walk together forever. That team will be together forever," he said. "The 2013 Ravens are going to attack the season with an enthusiasm unknown to mankind."