"Michael was in the [broadcast] booth with us during the 400-freestyle relay at the worlds in Barcelona last year, and I could see the anger and the helplessness he felt when the USA lost that race," Gaines said. "The moment I saw his face, I knew he'd be back. He knows he can help."
Stewart agreed. "I thought, 'That's it, he's back,'" Stewart remembered thinking in Barcelona. "Michael missed it. He's so competitive. If you want to make Michael Phelps happy, just challenge him."
He thinks Phelps could make a run at Rio, especially now that the swimmer is opting for less strenuous races and shorter distances.
"We're going to see a much more relaxed Michael Phelps, now that the 400 IM is off the table," said Stewart, who won two gold and one bronze medals in the 1992 Olympics.
"Can he be ready for the Olympics? Absolutely. As a pro athlete between 27 and 33, you've got the power and a lot of snap," he said. "As a pure fan, I'd really like to see just how fast Phelps can go. The 100 free got really interesting today."
Gaines dismissed fears that Phelps could damage his legacy by returning as an older and perhaps less dazzling swimmer.
"Whether he wins or loses, it doesn't matter," Gaines said. "He'll never be better at anything in his life than he is at swimming fast. He's younger than LeBron James. Should we tell James to retire because he finished on top last year? It's like asking a master woodworker to stop his craft because his last piece was perfect."
Tribune Newspapers reporter Philip Hersh contributed to this article.