Feliz began the 2015 season with Texas and posted six saves in his 18 appearances with the Rangers before signing with Detroit as a free agent on July 11. He finished the season with the Tigers, where he made 30 appearances and recorded a save in three of his last four outings.
"Neftali Feliz is a veteran relief pitcher with a quality pitch arsenal who showed signs of returning to his pre-injury form in 2014 and again at times in 2015," Pirates general manager Neal Huntington said in a statement. "He has shown the ability to pitch in high leverage situations in the past and we believe we can help him regain that form and be an important part of our 2016 bullpen."
The 27-year-old Feliz was a 2010 American League All-Star and was named the AL Rookie of the Year that season with the Rangers after posting a 2.73 ERA with 40 saves in a career-high 70 appearances. Feliz produced 32 saves with the Rangers in 2011.
Feliz made only 14 appearances over the next two seasons, undergoing Tommy John surgery on his right elbow in August 2012 and returning to action the following September.
In 2014, Feliz posted a 1.99 ERA over 31 2/3 innings with 13 saves in 30 games with Texas.
Since making his major league debut with the Rangers in 2009, Feliz has posted a 3.17 ERA with 97 saves in 246 games. He has also produced a 1.93 ERA over 18 2/3 innings with seven saves in 18 postseason games.
The Pirates also designated catcher Tony Sanchez for assignment. He was the fourth overall pick in the 2009 draft.