The 34-year-old guard said he was hurt by newspaper articles suggesting his best years are behind him.
"This year for me, it's personal. It's going to be like my rookie season all over again," Iverson said. "It hurts. I read the papers. I listen to some of the things people say ... about my struggles last season, saying I lost a step. They (are) trying to put me in a rocking chair already."
The Grizzlies took a one-year flier on him, signing him to an incentive-boosted deal that The (Memphis) Commercial Appeal reports will pay him $3.5 million.
Iverson, slowed by a back problem, averaged 17.5 points and 5.0 assists in 57 games for Denver and Detroit last season, well below his career averages of 27.1 and 6.2, respectively.
He is a former league MVP and nine-time All-Star.
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Michael Sam cut from the Dallas Cowboys