While the Giants have been quiet on the free-agent market, they could look to upgrade their roster via trades, and they have their eyes on an All-Star National League second baseman.The Giants and Seattle Mariners have emerged as the front-runners to acquire Brendan Donovan from the St. Louis Cardinals, The Athletic’s Katie Woo reported, citing sources familiar with negotiations.The 28-year-old Donovan has been a solid contributor for the Cardinals during his four-year MLB career, and he earned his first All-Star nod last season.In 118 games last season, Donovan slashed .287/.353/.422 with 32 doubles, 10 homers and 50 RBI. In 2024, he recorded career highs in doubles (34), home runs (14) and RBI (73).While Donovan primarily played second base in 2025, he predominantly played left field in 2024, so he would provide first-year manager Tony Vitello with a versatile option.Per Woo, the Giants and Cardinals have discussed several top prospects who could be part of a potential Donovan deal, including left-handed pitcher Carson Whisenhunt and 2025 first-round draft pick Gavin Kilen, who played for Vitello at Tennessee.Whisenhunt, 25, made his...