MESA, Ariz. — Leave it to the Cubs to turn collusion — or whatever it was that drove the free-agent market this offseason into the ground — into a market inefficiency to exploit for a competitive advantage.
As right-hander Yu Darvish’s six-year deal became official Tuesday, president Theo Epstein said it wasn’t until December that the budget-conscious Cubs realized they might be in play for the pitcher many rated as the top starter on the market.
‘‘He was atop our wish list, but early in the offseason, we didn’t think it was very realistic,’’ said Epstein, who entered the winter with the task of keeping the Cubs’ payroll under the luxury-tax threshold while filling two rotation holes and several bullpen needs.
‘‘Around the Winter Meetings, we got to a point just in assessing the supply and demand at the top of the starting-pitching market that we might be in a position to end up at least being a contender for Darvish with a contract that we could tolerate. It was a contract that we could fit into our short-term plan and our long-term plan.’’
The $126 million deal came together last weekend, when the Cubs added the sixth year to lower the annual average value (the figure used for luxury-tax purposes). The deal is front-loaded, with the highest salary — $25 million — in 2018 and the two lowest — $19 million and $18 million — in 2022-23.
Darvish, 31, expected to get a significantly bigger deal than that when the offseason began, and outside projections based on similar pitchers and recent free-agent signings seemed to agree.
With the help of a translator, Darvish said in Japanese that he didn’t think it was ‘‘appropriate’’ to talk about contract details and sidestepped a question about his surprise and disappointment with the pace of the free-agent market.
But National League rivals only can blame themselves if this signing puts the Cubs over the top and into another World Series.
The Cubs weren’t the only team willing to go to six years, according to sources, and some of the six other teams pursuing Darvish offered similar money, one source said. But all still were considered significant discounts when compared to expectations in the fall, suggesting a team might not have needed to get particularly close to those initial projections to outbid the Cubs.
The final deal put the Cubs close enough to their ceiling for avoiding the luxury tax that their flexibility for a trade-deadline deal might be compromised.
‘‘We do have some, not a ton,’’ Epstein said. ‘‘But it’s something we have to manage through the course of the year.’’
What the Cubs were able to offer Darvish was an opt-out clause after two seasons that theoretically might allow him a chance to sign for a higher annual paycheck if the markets return to recent norms and he performs well.
Darvish also has escalators based on Cy Young voting that can put an additional $15 million in reasonable reach during the life of the contract (capping at a long-shot $30 million).
At various points of the offseason, the Astros, Yankees, Rangers, Dodgers, Twins and Brewers were seriously in the mix for his services.
‘‘My priority in selecting a team was a team that had a great chance of winning the World Series,’’ said Darvish, whose two poor starts for the Dodgers last fall were a big reason they lost to the Astros in the World Series. ‘‘The Cubs obviously have more than a great chance of winning. So I’m really honored to be here.’’
A four-time All-Star with the highest strikeout rate in major-league history (11.04 per nine innings) suddenly is a big part of that great chance.
‘‘I am not one to count the chickens and all that kind of stuff,’’ Cubs manager Joe Maddon said. ‘‘It’s all theory right now. . . . We’ve still got to play the game on the field, and I’m really excited to see our product.’’
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