MINNEAPOLIS -- After a slow start to their offseason, the Twins made their first move to reinforce the starting rotation on Friday, when the team announced the signing of veteran left-hander J.A. Happ to a one-year contract.

Terms of the deal were not disclosed, but sources told MLB.com that it was worth $8 million.

Happ, 38, adds some needed depth to a starting group that was considerably thinned by the departures of Jake Odorizzi and Rich Hill from the 2020 rotation. As things stand, Happ should slide into the back of the rotation behind Kenta Maeda, José Berríos and Michael Pineda.

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Happ owns a 3.98 ERA over 324 career appearances and has pitched in 15 playoff games. The left-hander has been a consistent and durable pitcher across his 14-year MLB career, and he most recently spent two-plus seasons with the Yankees following a 2018 trade from Toronto. Though he struggled with home runs in '19 in the confines of Yankee Stadium, he rebounded with a solid '20 season in which he pitched to a 3.47 ERA and a 1.05 WHIP, the latter being the best mark of his career.

Fueled by less reliance on his four-seam fastball and increased usage of his sinker, Happ's underlying metrics were also better across the board in 2020. He lowered his hard-hit rate, barrel rate and average exit velocity allowed, and all of his expected statistics indicated that he was allowing less productive contact to hitters. In fact, his xERA of 3.28, per Statcast (a projection of ERA based on quality of contact), was by far his lowest since Statcast began tracking in 2015.

Another encouraging sign for Happ was that he started to miss more bats with his slider last season, generating a 31.7 percent whiff rate, a jump of more than 10 points from his 2019 mark. The Twins and pitching coach Wes Johnson have been aggressive in their usage and development of sliders over the last two seasons.

Happ's addition is also significant in that the Twins' starting rotation skewed heavily right-handed even before Hill departed in free agency.

There could still be room for the Twins to add more starting depth, as the club saw a rash of injuries throughout their rotation last season. Randy Dobnak could hold a starting spot after a solid 2020, but depth options Lewis Thorpe and Devin Smeltzer both struggled in their sophomore seasons.

The Twins also have strong upside waiting in the wings, as top starting prospects Jhoan Duran and Jordan Balazovic are likely to impact the Major League club at some point in 2021. A low-risk deal with a one-year commitment to a consistent veteran like Happ could continue to bridge the gap to those two young arms, giving them time to finish their development without being pushed too aggressively into big league action.

The club previously added right-handed reliever Hansel Robles on a one-year deal but has otherwise been quiet in the free-agent market.