Frazier, who was selected with the fifth overall pick in the First-Year Player Draft earlier this month, launched a home run on Tuesday in his debut with the Arizona League Indians. In his second at-bat, the 18-year-old Frazier showed off his power and speed with a triple.
Antonetti smiled when asked about Frazier's debut.
"It's obviously great for him to get off to such a great start," Antonetti said. "It's hard to script it any better than hitting a home run in your first professional at-bat. And then in the next at-bat, he demonstrated his other tools by hitting a triple. He put up some very good at-bats."
The Indians selected Frazier out of Loganville High School (Ga.), where he hit .485 with 17 home runs, 22 stolen bases and 45 RBIs in his senior season. On Tuesday, Baseball America named Frazier the magazine's 2013 High School Player of the Year.
On Wednesday, Indians shortstop Francisco Lindor -- the club's No. 1 prospect -- and relief prospect C.C. Lee were also named to the World Team's roster for the All-Star Futures Game.
"There are a lot of good things going on in our farm system," Antonetti said. "We've developed some guys that we were expecting some things coming into the year, as well as some guys that have developed maybe even more quickly than we would've thought.
"There have been a lot of positive stories in our Minor League system this year."
Jordan Bastian is a reporter for MLB.com. Read his blog, Major League Bastian, and follow him on Twitter @MLBastian. This story was not subject to the approval of Major League Baseball or its clubs.