The Colorado Rockies surrendered the most runs in Major League Baseball last year and began the offseason in a familiar position -- with a need to upgrade their pitching staff. But more than three months after their final game of 2014, the Rockies have yet to sign any free-agent pitcher to a major-league contract. The hitter-friendly environment at Coors Field is the same hindrance to new general manager Jeff Bridich as it was under his predecessor, Dan O’Dowd. As a result, sources say the Rockies have discussed outfielder Charlie Blackmon -- an All-Star last year -- in trade talks with multiple teams. Rockies officials believe they can trade Blackmon for a starting pitcher and replace Blackmon with a free-agent outfielder -- in this case, using the Coors effect to their advantage. The Atlanta Braves, Chicago Cubs, Texas Rangers and Baltimore Orioles are among the teams known to be seeking an outfield bat, sources say. The Rangers have had interest in Blackmon in the past, according to a source. The Rockies have spoken with the New York Mets about Dillon Gee this offseason, but Blackmon almost certainly would be too high of a price to pay for Gee alone. The Mets also appear set with their starting outfield of Curtis Granderson, Juan Lagares and Michael Cuddyer. Part of the Rockies’ motivation to trade Blackmon is that his value is at an all-time high right now, sources say. A late bloomer, Blackmon is in his prime (28 years old) but still four seasons away from being eligible for major-league free agency.