Many critics felt Nicks wasn't giving his all in order to protect himself from injury with free agency looming.
Nicks wasn't very productive in 2013. He had just 56 catches despite being targeted 102 times and failed to score a touchdown for the first time in his five-year career.
The 26-year-old receiver ultimately failed to land a huge payday and signed a one-year contract with the Indianapolis Colts in the offseason.
"I mean, anytime people say things like that and try to discuss your character, I think it takes a toll on anyone," Cruz said. "I think it did for him, and I think it's something where he wants to prove people wrong. He wants to show that he's a team guy, show that he gives his all and everything for his teammates. And I think the fresh start for him in Indy is gonna be just that, so we'll see how it goes for him."
Cruz felt last season was "tough" on Nicks.
"Obviously, he's a competitor and he wants to play and be able to do all of those things at a high level, and you could just see certain times throughout the game it just didn't look like he was himself," Cruz said. "Whether it was off-the-field things or things that he was battling on the field with injuries and things like that, you could just sense something was off. But I just tried to stay in his ear and keep him positive. It was a tough year for him, and I'm happy he's in a clear mind now and able to kind of lock in, as well."
In Anderson, Indiana, on Monday, Nicks was asked about Cruz's comments.
"I think that Cruz witnessed what I went through firsthand so I can see why he would say that," he said. "There was a lot of criticism I was taking when people didn't really realize what I was going through."
The Giants will face Nicks on Saturday night in Indianapolis.
Cruz is close with Nicks and plans to send his friend some trash talk via text before the preseason game.
"It's gonna be weird," Cruz said of seeing Nicks on the opposing sideline. "I was watching him this past week in that good old Colts jersey, and it's just not the same. He's healthy and in the best shape of his life, from what I hear and what I see."
ESPN.com Colts reporter Mike Wells contributed to this report.