Last January, the Giants signed lefties Derek Holland and Drew Pomeranz to one-year contracts, with mixed results. This year, Drew Smyly is the lefty joining the rotation mix.

The Giants announced Thursday that they've signed Smyly to a one-year, $4 million big league contract. Right-hander Trevor Oaks, claimed from the Kansas City Royals earlier this offseason, was DFA'd to clear a 40-man roster spot. Smyly can make an additional $3 million on bonuses tied to starting pitching and $1 million in reliever bonuses. He'll get a $250,000 bonus if he's on the opening day roster.

Smyly, 30, spent last season with Gabe Kapler's Philadelphia Phillies, posting a 4.45 ERA in 12 starts but averaging more than a strikeout per inning. He'll immediately join a crowded race to be in the Opening Day starting rotation, and he has a leg up simply because of the arm he throws with. The Giants are extremely right-handed on the roster, and Smyly joins Tyler Anderson as lefties who could help break up Jeff Samardzija, Johnny Cueto, Kevin Gausman, Tyler Beede, Logan Webb and others. Anderson currently is rehabbing from a knee injury.

Smyly has bounced around the American League for most of his career, and he put up good numbers before Tommy John surgery derailed him in 2017. Smyly had a 3.53 ERA in three years in Detroit and a 3.93 ERA in three seasons with the Rays. He was a good enough young pitcher that at one point he was included in a deal for David Price, but Smyly has struggled to stay in a rotation since having elbow surgery.

[RELATED: Joey Bart named second-best catching prospect in baseball]

Smyly didn't pitch in the big leagues in 2017 or 2018 and had 13 rocky appearances for the Texas Rangers in 2019. He was released by the Rangers and Milwaukee Brewers before catching on in Philadelphia, where he was a solid rotation piece down the stretch and posted a 3.65 ERA in five September starts.

The Giants had been looking for left-handed help, and Smyly should find himself with the same opportunity Pomeranz and Holland were given last year. Both started the season in the rotation and eventually ended up in the bullpen. Pomeranz turned into a nice trade chip, bringing Mauricio Dubon to San Francisco at the deadline.