Closer Wade Davis agreed to a three-year, $52 million contract with the Colorado Rockies, adding the best reliever on the free-agent market to an already-deep bullpen for the highest per-year salary ever at his position, a source familiar with the agreement told Yahoo Sports.

The 32-year-old Davis, ranked ninth in Yahoo Sports’ Ultimate Free Agent Tracker, turned in his fourth consecutive standout season as a reliever last year, paving the way for a $17.33 million-a-year commitment from the Rockies that includes a fourth-year vesting option that could push the total deal to $66 million. Davis passed a physical, and the Rockies are expected to announce the deal Friday.

Wade Davis is expected to close out games for the Colorado Rockies in 2018. (Getty Images) More

Though not as dominant for the Chicago Cubs as he was the previous three seasons for Kansas City, Davis’ regular-season excellence and playoff pedigree held wide appeal. A 2 1/3-inning, 44-pitch, division series-clinching performance this October personified Davis, who is revered by teammates and executives alike for his toughness. He helped lead the Royals to a World Series victory in 2015 after taking over as closer following an injury to Greg Holland.

In Colorado, he’ll do the same, albeit with a healthy Holland heading instead to free agency after returning with the Rockies from Tommy John surgery. Once considered a nonstarter for free-agent pitchers, Colorado has become a landing spot for top relievers this winter, with Jake McGee and Bryan Shaw signing three-year, $27 million deals and Davis turning the total guarantee outlay by the club on bullpen arms to $106 million. Adding to that the salaries of Adam Ottavino, Mike Dunn and Chris Rusin, the Rockies could spend upward of $45 million on their relief corps this season.

The fourth year of Davis’ deal vests as a $15 million player option if he finishes 30 games in 2020. Otherwise, it turns into a mutual option with a $1 million buyout. The deal’s average annual value bests Aroldis Chapman’s record of $17.2 million on a five-year contract.

Davis joined Chapman, Craig Kimbrel, Andrew Miller and Kenley Jansen in the discussion for the best reliever in baseball since 2014, when he transitioned to the bullpen after struggling as a starter when he arrived in Kansas City as part of the James Shields deal. He finished his first Royals season in relief with a 1.00 ERA, bested it the next season and didn’t allow a home run the year after that.

While his strikeout rate jumped in 2017, Davis’ control with the Cubs wavered, and he allowed an uncharacteristic six home runs in 58 2/3 innings. After a first half in which he posted a 1.46 ERA, Davis gave up 10 runs in 21 2/3 second-half innings and, along with Holland, was one of the few valuable relievers available after a deluge of signings at the Winter Meetings.

The market proved just fine for Davis after all. And with Davis, Shaw, McGee, Rusin, Ottavino and Dunn, the Rockies are banking on the most expensive bullpen in the National League – and right there with the New York Yankees for the highest paid in the major leagues – to help them challenge the Los Angeles Dodgers in the NL West and perhaps push them beyond the wild-card game, which the Rockies lost to Arizona this year.

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