Cubs' addition of Jon Lester the latest in Epstein's rebuilding process

SAN DIEGO — It's reunion time for Jon Lester, but not with the Red Sox. Lester has agreed to a six-year, $155 million deal with the Cubs, whose president of

SAN DIEGO — It's reunion time for Jon Lester, but not with the Red Sox. Lester has agreed to a six-year, $155 million deal with the Cubs, whose president of baseball operations, Theo Epstein, was the general manager of the Sox when the 30-year-old lefty broke into the majors back in 2006.

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In that regard, Lester is making the same gamble that Epstein did when he left Boston following the 2011 season. After winning two championships with the Red Sox, he is taking up the challenge of bringing a World Series to a franchise that hasn't won one since 1908. Epstein was the GM of the 2004 squad that ended the franchise's 86-year drought without a championship, as well as the '07 one, for whom Lester started the World Series-clinching game against the Rockies. After Epstein's departure, Lester served as the staff ace of the 2013 champions under general manager Ben Cherington.

The Cubs have been in rebuilding mode since Epstein and general manager Jed Hoyer, another transplant from the Red Sox front office, took over, stripping the roster of its high-salaried players from the previous regime. Consequently, Chicago has climbed from 61 wins in 2012 to 66 and 73 over the last two years, the most recent of which saw the arrival of top prospects Javier Baez and Jorge Soler. While the team is chockfull of position-playing prospects, with Kris Bryant and Addison Russell the most prominent ones still to come, the organization lacks comparable depth in pitching.

Lester immediately becomes the staff ace in a rotation that at the moment projects to include Jake Arrieta, Jason Hammel (who re-signed with the team on Monday after being traded to Oakland this summer), Kyle Hendricks and either Tsuyoshi Wada or Travis Wood. That starting five will have a new starting catcher to throw to, as the team acquired Miguel Montero from the Diamondbacks earlier in the day. The Cubs aren't likely to turn into contenders overnight via Tuesday's transactions, and as the base of prospects matures, there is the possibility that at least one of their high-upside infielders -- a group that also includes incumbent shortstop Starlin Castro-- will be traded in the service of further upgrading the pitching.

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Lester's contract, which also includes a vesting option for a seventh year, is tied with that of the Yankees' Masahiro Tanaka for the fifth-highest ever given to a pitcher. In terms of average annual value, its $25.83 million per year ranks second among all pitchers behind only Clayton Kershaw's $30.7 million. While Lester has never won a Cy Young award the way that Kershaw, Justin Verlander ($25.7 million per year), Felix Hernandez ($25 million per year), Zack Greinke ($24.5 million per year) or CC Sabathia ($24.4 million per year) have done, he timed the market well, both in attracting a championship-hungry big-market team with only $47 million in payroll committed for 2015 and in coming off one of the best seasons in his career.

Lester set career bests in innings (219 2/3), ERA (2.46, more than a run below his 3.58 career mark), FIP (2.80), walk rate (2.0 per nine) and strikeout-to-walk ratio (4.6) in a season split between the Red Sox and A's. With Boston last in the AL East at 48-60 on July 31, Cherington traded him to Oakland along with Jonny Gomes and cash in exchange for Yoenis Cespedes and a competitive balance draft pick. The A's, who had the best record in baseball at the time at 66-41, and who had just acquired Jeff Samardzija and Hammel from the Cubs in a deal for Russell and three other players earlier in the month, were going for broke, but they collapsed down the stretch and secured only a wild-card berth. Lester, who had continued to pitch well after being acquired, started the Wild-Card Game against the Royals and took a 7-3 lead into the eighth inning. However, he was left in too long and wound up allowing six runs in a game that Kansas City won in the bottom of the 12th to set off their amazing postseason run.

Lester's contract also contains a full no-trade clause and a $25 million vesting option for 2021 that can be attained if Lester pitches at least 200 innings in 2020 or at least 400 in 2019-2020.

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Though they offered Lester a well-below-market four-year, $70 million extension in the spring, at the time the Red Sox dealt him, the presumption throughout the baseball world was that they would be in the mix to re-sign him once he reached free agency. Indeed they were, though according to Yahoo! Sports' Jeff Passan, their final offer was six years and $135 million, well off the mark. Even so, Lester did not sign with the highest bidder; according to Passan, the defending world champion Giants -- who have a pretty fair lefty by the name of Madison Bumgarner already on staff — offered seven years and "somewhere in the neighborhood of $168 million." The Dodgers, whose pursuit emerged relatively late in the process, made an offer said to be similar to the Cubs, but without the personal ties that Chicago offered.

As with any long-term deal, this one carries a considerable amount of risk, particularly for a pitcher in his age 31-36 seasons. That said, Lester has been relatively free of arm troubles during his nine-year major league career, with a 19-day stint on the disabled list in 2011 for a strained latissimus dorsi his only significant injury since missing time due to lymphoma in 2006-07. The team still needs a whole lot more work until they can contend for a championship, but if he helps bring one to Wrigley Field, it will all be worth it.