The deal is estimated to be worth about $30 million over six or seven years, Passan reports. Last year, compatriot Raisel Iglesias inked a seven-year contract worth $27 million pact with the Cincinnati Reds.
Sierra, 25, posted a 16-21 record in 131 appearances with a 4.23 ERA, 1.49 WHIP and 221 strikeouts in 131 games for Holguin and Sancti Spiritus of the Cuban National Series.
The Miami Marlins also expressed interest in Sierra.
- Christopher Chavez