Preliminary indications suggest Costello died of natural causes.
Born in Hartford, Connecticut, Costello played minor league baseball for the Clinton Lumberjacks and later for the Fort Myers Miracle during their 2018 championship run.
"On behalf of our staff and families, and others who have supported Ryan throughout his career in professional baseball, I want to express our deepest condolences to the Costello family. Ryan was an absolute pleasure to work with," English said.
"We join the players, coaches, and staff members of the Minnesota Twins, Seattle Mariners, Pensacola Blue Wahoos, Fort Myers Miracle, Clinton LumberKings, Arizona League Mariners, Auckland Tuatara, Central Connecticut State University, and Wethersfield High School in offering our unwavering support to Ryan's family during this difficult time.
"We wish the days of sorrow one day soon can turn to days of joy in celebrating all that was – and is – good about Ryan's life and spirit. He was an inspiration to many on the field, advancing to Double-A ball after being selected as a 31st-round pick by the Mariners in 2017.
"He was a champion. He won the Florida State League title in 2018 with his Miracle teammates, hitting a go-ahead home run in the series-clinching Game 4. Ryan's hard work and dedication to his craft were admirable, and we were blessed to be alongside him as he lived out his dream of playing professional baseball."
In a statement the Tuatara said support is being offered to Costello's teammates, who are "naturally devastated" by the news.
"The Tuatara express their deepest condolences to Ryan's family back home in the United States and to the whole Minnesota Twins organisation," the club said in the statement.
In an interview with Twins Daily, an outlet dedicated to team news, Costello said in October 2018 that his greatest strength is "my ability to stay positive through tough times and understand that it's part of the game and ups and downs are going to come."
He spoke of his desire to spend time with family after his first professional season in 2019.
"My dad has a bass boat and has had it since I was a kid," Costello said. "The first thing we do when I go home is go fishing.
"I've been home for seven days, I've been out fishing about four of those days. I live about five minutes from a river, the Connecticut River, so we go fishing on the river a lot."
