The first month of the regular season isn't even over and the Philadelphia Phillies are thinking about ways to improve.

Philadelphia is already "doing due diligence" and looking at the starts of San Francisco Giants left-hander Madison Bumgarner, sources told MLB Network's Jon Morosi.

Will the Giants trade Madison Bumgarner this season? @jonmorosi gives us insight on this possibility and where he might be traded to. pic.twitter.com/zO9YofeCOy — FOX Sports: MLB (@MLBONFOX) April 12, 2019

Bumgarner is eligible for free agency at season's end and appears to be a perfect trade candidate with the Giants likely heading in a different direction under first-year general manager Farhan Zaidi.

The 29-year-old Bumgarner would fit in nicely with the Phillies, giving them a tremendous top three in their rotation alongside Aaron Nola and Jake Arrieta. He'd be affordable, as he's making just $12 million this season.

As a veteran with a sparkling resume, Bumgarner could also help increase the Phillies' chances of making the postseason for the first time since 2011.

Career numbers - regular season

IP ERA FIP WHIP SO 1657.1 3.04 3.27 1.11 1607

Career numbers - postseason

IP W-L ERA WHIP SO 102.1 8-3 2.11 0.90 87

The Phillies - who added Bryce Harper, Andrew McCutchen, and a slew of other players during a busy offseason - are already in a tight race in the NL East. They're currently in second place with a 7-4 record, trailing the New York Mets by a half-game.