Diaz still needs to undergo a physical, and the deal must be approved by Major League Baseball before it becomes official.
Diaz is regarded as one of the top power-hitting prospects in the Dominican Republic, and his frame has been compared with that of Ryan Howard of the Phillies. The 6-foot-4, 210-pound left-handed hitter is an outfielder but could be moved to first base if he continues to grow.
The Twins have $3.9 million to spend on international free agents this year, and the $1.4 million for Diaz takes up a large chunk of that, but the Twins are expected to be active in the international market, according to general manager Terry Ryan.
"We'll be active everywhere internationally -- in the Dominican, Venezuela, Europe, Australia, Asia," Ryan said. "Every team has money earmarked for international signings, and we hope to spend it all. It won't just be one guy. It'll be a bunch."