Hot Stove Tracker
Allen played for three Major League clubs -- the D-backs, A's and Rays -- from 2009-12, and he had a career .203/.290/.375 line. Turning 30 in February, the lefty hitter spent the past two seasons with the Mets' organization at the Triple-A level. For Las Vegas in 2015, Allen batted .273/.350/.478 with 16 home runs and 68 RBIs in 124 games.
Melville, 26, was 7-10 with a 4.63 ERA in 27 starts last season for the Tigers' organization in Triple-A Toledo. He was originally a fourth-round pick of the Royals in the 2008 Draft.
Diaz, who turns 27 on Feb. 10, spent the past two seasons in the Red Sox's organization. Combined at Double-A and Triple-A in 2015, the reliever was 2-1 with a 1.73 ERA in 37 games. In 72 2/3 innings, he allowed 54 hits and 30 walks with 66 strikeouts and a 1.156 WHIP.
Ramirez, 27, split the 2015 season with the Mariners' and D-backs' organizations. In 37 relief appearances combined at Triple-A, he posted a 2.72 ERA. In 20 big league games, he had a 5.32 ERA. Arizona purchased his contract from Seattle on July 27. Ramirez also pitched in 18 Major League games for the Phillies in 2013.
Cincinnati is trying to overhaul its bullpen this offseason and is clearly trying to add depth for competition at camp.
Mark Sheldon is a reporter for MLB.com. Read his blog, Mark My Word, follow him on Twitter @m_sheldon and Facebook and listen to his podcast. This story was not subject to the approval of Major League Baseball or its clubs.