Robertson, who could be seeking a four-year deal, is generally regarded as the top closer on the free agent market. The major drawback for Robertson is the attachment of the qualifying offer, as teams will have to weigh the risk of giving up a first round draft pick just to land a relief pitcher. Some potentially cheaper options for the Astros could include Andrew Miller or Sergio Romo, both of whom are entering the free agent market for the first time.
Along with signing a closer, the Astros are also focusing on moving Jason Castro and Dexter Fowler, according to Nick Cafardo of the Boston Globe. Both Castro and Fowler will be free agents after 2015, and the Astros wouldn't mind dealing players that are unlikely to be in Houston long-term.
Castro, a left-handed hitting catcher, has been a potential trade target ever since the Astros acquired Hank Conger from the Angels. As he enters his final arbitration year, Castro will likely land a 2015 salary close to $4 million. Castro struggled through most of the the 2014 season, and finished with an OPS of .652. The disappointing season followed up an All-Star appearance in 2013, as Castro posted a slash line of .276/.350/.485 and WAR of 4.3, according to Fangraphs.
Fowler, like Castro, will enter his final year of team control in 2015. After posting a .784 OPS in 2014, the switch-hitting outfielder is slated to earn a $7.35 million salary in 2015, according to Cot's Baseball Contracts. Even though Fangraphs grades Fowler's defense in center field as below average, Fowler's high walk rate and OBP skills could appeal to many teams. For his career, Fowler has posted a .366 OBP, which is good for 19th in the MLB since 2008.