Sources: St. Louis Cardinals to acquire Nolan Arenado from Colorado Rockies

The St. Louis Cardinals are finalizing a trade to acquire star third baseman Nolan Arenado from the Colorado Rockies, a blockbuster that still needs various approvals but is expected to be completed in the coming days, sources confirmed to ESPN on Friday.

The complicated deal took months of on-and-off discussions and gained momentum in recent weeks when the Rockies committed to sending around $50 million to help cover a portion of the six years and $199 million remaining on Arenado's contract, sources said.

If finalized, the deal would include multiple adjustments to Arenado's contract, including an additional year guaranteed at $15 million, an additional opt-out clause and a reinstatement of the no-trade clause he must waive to consummate the trade.

Because a significant amount of money would be moved, the deal is subject to approval by Major League Baseball. Similarly, because Arenado is expected to defer money and amend his contract, the MLB Players Association must sign off on it.

If the deal is seen through to the finish line, the Cardinals would significantly bolster their status as the favorite in the National League Central, the Rockies would trade their franchise player just two years into a deal that was supposed to keep him in their uniform until 2026, and Arenado would leave the only team that he has played for -- and one he sought a trade from after he believed it had done a poor job building around him.

Arenado, 29, has won a Gold Glove in each of his eight seasons in Colorado, where he developed into one of the best players in baseball. Before the 2019 season, he signed an eight-year, $260 million extension with the Rockies, who drafted him in 2009 and were committing to becoming perennial contenders.

The team almost immediately struggled, frustrating Arenado and carving the path for a deal to St. Louis, which tried to trade for him before the 2020 season and finally succeeded a year later. The return for the Rockies is not expected to be significant, with pitcher Austin Gomber and low-level prospects among the players who have been discussed.

In Arenado, the Cardinals get an across-the-diamond complement to first baseman Paul Goldschmidt, another veteran right-handed hitter they acquired via trade. The market for Arenado wasn't altogether robust because of the significant money remaining on his deal. For months, the Cardinals and Rockies haggled before coming to an agreement Friday night.

The Cardinals locked up longtime starter Adam Wainwright on an $8 million deal Thursday, and longtime catcher  Yadier Molina has indicated in recent days he is likely to return to the Cardinals, particularly if they could acquire Arenado, sources said.

The Rockies were looking both to escape from the significant commitment to Arenado and to avoid the possibility of him triggering the opt-out clause in his contract that follows the upcoming season. As part of a restructured deal -- in which Arenado would also defer money -- he will receive another opt-out clause after 2022, tack on a seventh year in 2026, guarantee himself $214 million over that time and maintain his no-trade clause.

Colorado could receive Gomber, a 27-year-old left-hander who was excellent in a swing role last season. Multiple prospects have been discussed, according to The Athletic, which was first to report the deal. While power-hitting first baseman Luken Baker's name was reported as part of the potential prospect package, he is not expected to be in the deal, a source told ESPN.

With Colorado paying down a significant portion of Arenado's future salary, St. Louis will pay him about $25 million a year and bump its payroll to around $160 million.

A five-time All-Star, Arenado struggled at the plate during the abbreviated 2020 season, hitting .253 with eight homers before missing the final nine games with a left shoulder bone bruise. The down year came after he hit a career-best .315 with 41 homers and 118 RBIs in 2019.

After the trade of Troy Tulowitzki, Arenado became the linchpin of the Rockies, helping lead them to a 2018 wild card. His extension was supposed to have kept him with Colorado for perhaps the remainder of his career, but his relationship with general manager Jeff Bridich soured and Arenado clearly wanted out this winter.

In December, Rockies manager Bud Black downplayed rumors that Arenado and shortstop Trevor Story would be traded, saying, "My expectation is that they'll be with us come Opening Day."

Arenado won't be. And if Colorado can't come to an extension deal with its All-Star shortstop, Story could be on the move at some point this season, too, with the Rockies not wanting to potentially lose him via free agency in the winter of 2021-22.