TAMPA — Aaron Boone said Saturday that Aaron Hicks was underrated. Monday morning, Hicks and the Yankees agreed to a seven-year, $70 million extension that will keep him off the free-agent market.

The deal begins this season, when the switch-hitting Hicks was scheduled to make $6 million. Hicks, 29, is coming off a career year in homers (27), RBIs (79), games played (137) and runs (90).

Since being acquired from the Twins for catcher John Ryan Murphy after the 2015 season, Hicks has turned into the Yankees’ regular in center field, where he is an elite defender.

In the past two seasons, Hicks has combined to hit .255 with 42 homers, 131 RBIs and an .838 OPS. He has been on the DL four times in three years with the Yankees, once with hamstring issues and three rib cage problems.

Signing Hicks is the Yankees’ second extension of camp. The Yankees gave staff ace Luis Severino a four-year deal for $40 million with a team option for $15 million.

Last week Dellin Betances said his agent, Jim Murray, and GM Brian Cashman were talking about an extension. Betances is eligible for free agency after this season.