Alvarez lost all four of his starts in 2015 before undergoing season-ending surgery on his shoulder.
Passan reported the deal would be for one year and around $4 million, with additional incentives available.
The team has not confirmed the deal but Alvarez posted a photo to his Instagram page with a message in Spanish that expressed his happiness in joining the team for 2016.
Henderson was non-tendered by the Marlins last month, becoming a free agent. The 25-year-old made the 2014 National League All-Star team while going 12–7 in what was his fourth major league season with a 2.65 ERA, 111 strikeouts and three shutouts in 30 starts for Miami.
Henderson struggled at the beginning of 2015, losing all four of his starts and allowing 18 runs in 22 1/3 innings. He underwent surgery on his right shoulder and missed the remainder of the year. He may start the 2016 season on the disabled list.
In 2013, Henderson was part of the Toronto Blue Jays' trade that sent him, Anthony DeSclafani, Yunel Escobar, Adeiny Hechavarria, Jake Marisnick, Jeff Mathis and Justin Nicolino to the Marlins in exchange for Emilio Bonifacio, John Buck, Mark Buehrle, Josh Johnson, Jose Reyes and cash considerations. He finished the season by tossing a no-hitter against the Detroit Tigers.
- Christopher Chavez