SAN DIEGO — Pitcher Jon Lester agreed Tuesday night to a $155 million, six-year contract with the Cubs, the first big deal of the offseason involving a top-level starting pitcher and one Chicago hopes will help end more than a century of frustration at Wrigley Field’s Friendly Confines.

Lester’s contract, agreed to on the second day of baseball’s winter meetings, contains an option for 2021 that, if it becomes guaranteed, would make the deal worth $170 million over seven seasons. The average annual value of $25.8 million is the second-highest for a pitcher behind Clayton Kershaw’s $30.7 million as part of a $215 million, seven-year deal with the Los Angeles Dodgers that began this year.

“It’s not often you get to win the lottery, and we won the baseball lottery this year,” new Cubs manager Joe Maddon said. “Now it’s up to us to put it into effect.”

A three-time All-Star who turns 31 next month, Lester won two World Series titles with the Red Sox and he was Boston’s clear first choice. But even before Jon Lester chose to sign with the Chicago Cubs, the Boston Red Sox were exploring all their rotation options.

With or without Lester, Boston general manager Ben Cherington thinks results are what matters most.

“I think our fans expect us to deliver on the field and win games,” he said. “In order for us to give the best chance, we have to add to the pitching staff. There are all sorts of ways to do that. Of course there’s a connection to certain players more than others. But ultimately they care about the people we put on the field.”

The left-handed Lester will be reunited with Theo Epstein, former Boston GM, and joins a long-suffering team with a promising core of young players and a top-tier manager Maddon, who left Tampa Bay and signed a $25 million, five-year contract with the Cubs. Now, Chicago has an ace to lead the rotation as it tries to end a run of five straight losing seasons and a championship drought that dates to 1908.

Lester was dealt by the Red Sox to Oakland at the trade deadline in July and helped the A’s reach the playoffs for the third straight year before a 9-8, 12-inning loss to Kansas City in the AL wild-card game. He went 16-11 with a career-best 2.46 ERA and 220 strikeouts last season and is 116-67 with a 3.58 ERA in nine big league seasons.

Lester is headed to a team that hasn’t made the playoffs since 2008, but he knows Cubs president of baseball operations Theo Epstein and general manager Jed Hoyer from their time together in Boston.

Maddon had been used to small payrolls in Tampa Bay.

“I’ve not been on this side since my days with the Angels, when I got an email in Italy that we had signed Vldamir Guerrero,” said Maddon, who was a coach in Anaheim before switching to Tampa Bay. “I think that definitely sends that message how Theo and the group feel about this particular group. But understand, we have a lot of young players that have to grow up as quickly as possible. But having Jon there adds to the flavor and the possibility.”

The Cubs’ management is making over the team in a big way.

Chicago has a pending $20 million, two-year deal with right-hander Jason Hammel, traded by the Cubs to Oakland last summer. Earlier Tuesday, Chicago acquired All-Star catcher Miguel Montero from Arizona for minor league right-handers Jeferson Mejia and Zack Godley — a deal that added $40 million in salary to the Cubs’ payroll over the next three years.

Chicago’s rotation is likely to also include Jake Arrieta, Travis Wood, and Kyle Hendricks.

The Cubs also have a pair of All-Stars in the batting order in first baseman Anthony Rizzo and shortstop Starlin Castro and expect improved performances from young sluggers Javier Baez and Jorge Soler. Ahead is another wave of prospects that includes third baseman Kris Bryant and shortstop Addison Russell.

Maddon hopes an addition such as Lester helps change the mindset in the clubhouse when spring training starts in February,

“It definitely makes it more believable to everybody else in that room,” he said. “I’ll stand up and make the same speech regardless, but when you have it backed up by that particular kind of presence, it adds to it.”