Fifteen months after signing him to the largest free-agent contract in franchise history, the San Diego Padres are discussing trading pitcher James Shields to the Chicago White Sox, according to the San Diego Union-Tribune.

The Padres signed Shields to a four-year, $75 million deal as part of an offseason spending spree designed to help them keep pace with Dodgers and Giants in the NL West, but the team finished 74-88 and in fourth place last season and is 20-29 and in fifth place this year.

Shields, 34, was 13-7 with a 3.91 ERA -- his highest since 2010 -- last season but has bounced back in 2016 with a 3.06 ERA despite a 2-6 record.

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The Union-Tribune cited sources indicating the trade talks have "significant momentum." The White Sox are 27-22 and in first place in the AL Central, but they are 4-12 in their last 16 games after a 23-10 start.

Shields is owed $63 million by the end of the 2018 season, and the Union-Tribune reports that the Padres are willing to absorb some of that salary to facilitate a trade. Before signing with the Padres, Shields had spent his first nine major league seasons in the American League -- pitching seven years with the Rays and two years with the Royals.