"That's not for Landon to talk about," Shurmur told reporters Saturday. "The important thing is let's let Ereck talk for Ereck when he gets here, and we'll talk about that later. I don't think our players should be talking about another player's situation."
On Boomer and Gio on May 4, Collins said Flowers was "unhappy" the Giants signed offensive tackle Nate Solder in free agency.
Solder, who spent the first seven years of his career with the New England Patriots, signed a four-year deal worth up to $62 million to take Flowers' spot as New York's starting left tackle.
Giants general manager Dave Gettleman told reporters after Solder joined the team that Flowers could start at right tackle if he wins the job during training camp.
Collins has spoken out publicly about his teammates before. He issued an apology in December after he called Eli Apple a "cancer."
Shurmur was hired by the Giants to turn around a team that finished with the NFC's worst record (3-13) in 2017. He served as the Minnesota Vikings' offensive coordinator last season and was 9-23 in two seasons as head coach of the Cleveland Browns in 2011-12.