TAMPA, Fla. -- Two days after it was suggested that Aaron Hicks could be the most underrated player in the game, the Yankees showed the world just how much they think of their switch-hitting center fielder.

Hicks and the Yankees completed a seven-year, $70 million contract extension with a club option for the 2026 season on Monday. The deal replaces Hicks' one-year, $6 million contract for '19 that was previously announced on Jan. 11.

"The reason why I signed this deal was, I thought it was a fair deal for both sides," Hicks said. "I want to be here. The guys in the clubhouse, I want to fight for them. I want to go to war with them, which is the main reason why I signed the deal here."

Hicks, who welcomed son Aaron Jr. in January, joked that he also "won't have to worry about buying diapers; I'm extremely excited about that." General manager Brian Cashman said that discussions with Hicks' agent, Joe Urbon, had been ongoing since at least December.

The contract includes a $12.5 million club option for 2026, with a $1 million buyout, and a $2 million signing bonus. Hicks will be paid $10.5 million annually from 2020-23, and $9.5 million from 2024-25.

"I told Aaron, 'I'm betting on you,'" Cashman said. "I believe there's more gas in his tank. I believe there's more mountains to climb. He's a player with plate discipline and power and a cannon of an arm as a defender in center field, so he's capable of impacting a game in a positive way on both sides of the ball. I feel like we're fortunate to have him."

Prior to the Yankees' first exhibition of the spring on Saturday, manager Aaron Boone had opined that Hicks does not receive the credit that he deserves in some circles, proclaiming that the 29-year-old may be "the most underrated player in the game."

"We've got a premium player that in a lot of ways grew up and developed here," Boone said. "It's exciting for us all. I'm glad this is behind him now. He's really hungry to go out and show that not only is he the player he's shown us the last couple of years, but maybe there's more in there."

As 2019 dawns, Hicks will be seeking to improve upon a year in which he set career highs in homers (27), extra-base hits (48) and RBIs (79), compiling a .248/.366/.467 slash line in 137 games.

"I feel like the offseason right before last season was big for me," Hicks said. "I cleaned it up, started training better, started eating better. I got an amazing trainer in Abdul Sillah, and just by doing little things like that, I have changed how I play throughout the season. I felt strong throughout the season, all the way until the end."

In announcing the deal, the Yankees provided a cornucopia of statistics and advanced metrics, which better illustrates Hicks' value than traditional measures like his .236 career batting average.

For example, Hicks has posted an .838 OPS with a .368 on-base percentage over the past two seasons. He is one of eight American League players to reach both of those marks with at least 200 games played, along with José Altuve, Mookie Betts, Alex Bregman, Aaron Judge, J.D. Martinez, Jose Ramirez and Mike Trout.

Among Major League outfielders over the past two seasons, Hicks' 8.2 WAR (FanGraphs) ranks 12th, and sixth among center fielders. The club also pointed to a 15.5 percent walk rate that ranked fifth in the Majors last year, and a 20.9 percent chase rate that was seventh-lowest.

The only other American League center fielders to post a season with at least 25 home runs and a walk rate of 15 percent or better are Mickey Mantle (nine times), Trout (four times) and Larry Doby (twice).

"He's that poster child of controlling the strike zone," Boone said. "He does it just about as well as anyone in the game. The ability to not only do that, but couple it with power from both sides of the plate and do it at a premium position is so valuable."

Hicks' extension is the second significant move of the spring as the Yankees attempt to secure their young core. Right-hander Luis Severino bypassed arbitration earlier this month by agreeing to a four-year, $40 million extension.

The Yankees have also expressed interest in extending right-hander Dellin Betances and shortstop Didi Gregorius, both of whom are eligible for free agency after the season, as well as possible deals with younger players like Judge and Gary Sánchez.

"I believe this team has World Series potential," Hicks said. "That¡¯s what we¡¯re going for. If you are playing this game, you want to win a World Series. I believe that we can win a lot here if we all stay on the field and keep pushing toward the ultimate goal."