The Brewers will receive four minor-leaguers: left-hander Josh Hader, right-hander Adrian Houser and outfielders Brett Phillips and Domingo Santana.
Earlier Thursday, agent Scott Boras, who represents Gomez, and the Brewers said there is no medical issue significant enough to halt any trade.
"Carlos never had any issue with his hip," Boras told the Milwaukee Journal Sentinel. "He had an abductor and groin issue a few weeks ago; and, just to make sure he was OK, we requested the team do an MRI that showed his abductor had healed with medication. The doctor just happened to throw in, 'By the way, his hip structurally and tissue-wise is clean.' So, we have evidence that a doctor on record said his hip in fact was clean. So, why did this become an issue?"
Gomez was sought by the Mets as an upgrade in the outfield with Michael Cuddyer on the disabled list. The teams had agreed Wednesday to a deal that would send Gomez to New York in exchange for injured pitcher Zack Wheeler and infielder Wilmer Flores.
Mets general manager Sandy Alderson issued a statement scuttling the deal.
Brewers general manager Doug Melvin said Thursday in a FOX Sports interview, "There's no issue. We don't feel there's anything wrong with his hip."
Gomez was batting .260 with eight home runs and 20 doubles entering Thursday's game. Gomez, 29, is a two-time All-Star signed through 2016.
Fiers, 30, is 5-9 with a 3.89 ERA in 21 starts for the Brewers.