MIAMI -- The Miami Marlins traded a promising rookie pitcher on Wednesday for a prospect they hailed as their shortstop of the future.
In another deal, the Marlins traded right-handers Trevor Richards and Nick Anderson to the Tampa Bay Rays for right-hander Ryne Stanek and minor league outfielder Jesus Sanchez, another touted prospect.
With last-place Miami likely at least two years away from contention, the trades further fortify a farm system that is much improved since Derek Jeter's group bought the team in October 2017.
"It's just a continuation of what the goal is, and that is to acquire championship-level talent," president of baseball operations Michael Hill said.
Gallen, who turns 24 on Saturday, is 1-3 with a 2.72 ERA in seven starts since he made his major league debut on June 20. The Marlins thought they could part with him because depth in young pitching has lately been the strength of their organization.
Chisholm, 21, was rated the Diamondbacks' No. 1 prospect. He batted .204 with 18 homers and 13 stolen bases this season for Double-A Jackson.
"He's a rare combination of speed and athleticism and power batting from the left-handed side and a player that we think is going to be a tremendous big leaguer," Hill said.
A native of the Bahamas, Chisholm is a career .253 hitter in the minors, with 53 homers in 292 games since 2016.
Gallen pitched at North Carolina and was a third-round draft choice by the St. Louis Cardinals in 2016. He was traded to the Marlins in the deal that sent slugger Marcell Ozuna to St. Louis in December 2017.
Gallen said that when he was told about the trade, he thought it might be a joke.
"I've been through this once before," he said. "You can never know what's going to happen in this game. It's ever-changing. ... I'm excited for the opportunity with the Diamondbacks."
Gallen allowed two runs in seven innings Tuesday in a loss to the Minnesota Twins.
Sanchez, a 21-year-old left-handed hitter, hit .275 this year with Double-A Montgomery. Stanek has been used mostly as an opener by the Rays this year, and he has a 3.40 ERA in 41 games.
Richards, who recently lost his spot in the Marlins' rotation, is 3-12 this year with an ERA of 4.50. Anderson has a 3.92 ERA in 45 games of relief this year.