DETROIT -- The White Sox acquired right-handed starter James Shields from San Diego in exchange for Minor League starter Erik Johnson and infielder Fernando Tatis Jr., as announced by the teams on Saturday.

San Diego also provided significant cash considerations with $58 million still owed to Shields. The White Sox will pay $27 million of what's remaining, with $5 million coming this season and $10 million in each of the next two seasons if the veteran hurler doesn't opt out after the '16 season, as he contractually can.

A $16 million club option exists on Shields for '19, with a $2 million buyout.

"We are quite pleased to add a pitcher of James' caliber to our rotation," said White Sox general manager Rick Hahn during a Saturday evening conference call. "It's going to provide some stability and depth to the rotation. James' presence is not only going to make that rotation stronger, but it's going to have a positive effect on the bullpen given his ability to go deeper into games and therefore leave fewer innings for the bullpen to cover on a weekly basis."

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"He's been around. He's a veteran. He's a workhorse. I think you know what you are going to get from him," said White Sox ace Chris Sale, who suffered the loss in Saturday's 7-4 setback to the Tigers. "Hopefully he hits the ground running. I think he'll mesh in well. Hopefully that's the spark we needed."

Shields, 34, was scheduled to start Sunday night in San Diego against the Rockies, coming off of a dreadful 2 2/3 innings performance against the Mariners on May 31 in which he allowed 10 runs on eight hits, with one strikeout and four walks. Shields will join the team Tuesday in Chicago, but it's unknown when he will make his White Sox debut or whether he replaces Mat Latos or Miguel Gonzalez in the rotation.

Hahn acknowledged Saturday one of those two starters could move to the bullpen in the short term, or even long term.

According to one National League scout, Shields is believed to be a better fit on a team in contention, which is the case for the White Sox in the American League Central despite a 6-17 record over their last 23 games. Shields has nine straight seasons of at least 200 innings pitched, 30 starts and double-digit victories.

"You have to have a lot of respect for him," Sale said. "It's not easy. You don't just roll out of bed and throw 200 innings. For him, it seems like it's that way. But it just takes stress off of everybody else. Takes stress off the next starting pitcher. Takes stress off the bullpen. He's going to give us some quality innings as well."

This season stands as win-now mode for the White Sox. And while they don't intend to mortgage their future in terms of trading away top prospects such as shortstop Tim Anderson or right-handed pitcher Carson Fulmer, they are definitely looking to enhance their chances for October baseball in a division race that looks as if it will go down to the final weeks.

They still have prospects and budget room to work with while looking for a left-handed bat and potentially another reliever.

"It's our expectation," said Hahn of making greater roster changes. "We obviously see the games like you all do and realize there are other areas of need on this roster potentially over the coming months. While the rotation was certainly a very important one, and frankly one we felt was going to be fairly difficult to address in the coming weeks leading up to the [Aug. 1 non-waiver] Trade Deadline given the supply and demand out there, we felt it was an important one to move on early.

"But it's not the only need we see on this roster. Whether it's from a prospect standpoint or an economic standpoint, we do feel like we are in a position over the coming weeks and months to augment the roster if the opportunities arise."

A White Sox connection exists for Shields, as he is the cousin of Aaron Rowand, the center fielder on the 2005 World Series champion and currently the organization's outfield/baserunning coordinator.

Fantasy spin | Fred Zinkie (@FredZinkieMLB)

Even though Shields adds a useful workhorse to the White Sox rotation, Saturday's trade may diminish his fantasy value. The right-hander disappointed owners during his Padres tenure, posting a 4.00 ERA, a 1.36 WHIP and a 1.4 HR/9 rate across 44 starts. Now set to face deeper lineups in the AL with the backdrop of homer-happy U.S. Cellular Field rather than pitcher-friendly Petco Park, the veteran could struggle to post stats worthy of a consistent mixed-league roster spot. However, AL-only owners should be happy to make a significant investment in a starter with a 9.1 K/9 rate since the outset of 2015.

In San Diego, Erik Johnson could soon get a long look in the rotation. The right-hander should remain on mixed-league waivers for now given his 4.50 ERA and a 1.57 WHIP across 18 big league starts, but he's had solid Minor League success (career 3.23 ERA, 1.25 WHIP) and could contribute in deeper formats later this summer.