Brewers amateur scouting director Bruce Seid liked Diaz's speed but also his maturity between the lines as a young player.
"For a high school player, he's a good baseball player," Seid said. "He has a chance to hit for some power and again, love the speed."
The 5-foot-11, 175-pound Coral Springs, Fla., native batted .478 with a .620 on base percentage, seven home runs, 22 RBIs and 44 runs scored in his senior season.
The speedy right-handed hitter will play college ball at Florida International if he does not sign with the Brewers.
Diaz was the second of three outfielders selected by Milwaukee and second center fielder in a row behind Omar Garcia.
Kevin Massoth is an associate reporter for MLB.com. This story was not subject to the approval of Major League Baseball or its clubs.