White Sox acquire James Shields from Padres

The White Sox have made the first big splash of the trading season. They've acquired James Shields from the Padres in exchange for right-handed starter Erik Johnson and infield prospect Fernando Tatis Jr.

Chicago has had a major need at the back end of their rotation, and Shields will likely give them a boost there. Chris Sale, Jose Quintana and Carlos Rodon have all pitched well, and Miguel Gonzalez has been effective at eating innings if nothing else. The man that Shields will likely be replacing, Mat Latos, is sporting a rather ugly 5.35 DRA through 56 innings pitched.

Shields, for his own part, has a 4.75 DRA this year. He's been striking out two fewer batters per nine innings (7.6, down from 9.6) while his walks have remained static. The White Sox employ one of the better pitching coaches in the league (Don Cooper), so it's possible that Shields could fix himself to a certain degree. Because U.S. Cellular Field is a hitter's park, Shields will have little margin for error. He's had a good career to this point (lifetime 3.51 DRA and 43.1 WARP) and was relatively effective last year, so Cooper should have enough to work with.

According to Ken Rosenthal, the Padres are throwing in more than $30 million in cash to cover some of Shield's remaining salary. Shields does have an opt-out clause that he can exercise at the end of the year, but it's hard to imagine him leaving his remaining $42 million in salary on the table to test free agency again. If he does opt out for whatever reason, the Padres will recover a corresponding amount of the money.

The two players that San Diego are receiving couldn't be more different. Johnson is a former top prospect but has failed to latch on in limited big league action. In 98 career innings at the highest level, Johnson has pitched to a 4.50 ERA and surrendered nearly two home runs per nine innings. Johnson is still just 26 years old, though, so a move to the more spacious confines of San Diego could do him well. He also hasn't made a relief appearance since rookie ball, meaning an eventual move to the bullpen may still be in the cards.

Tatis, who signed with the White Sox out of the Dominican Republic last summer for $700,000, is indeed the son of the man who once hit two grand slams in the same inning. Tatis was one of the more notable prospects of last year's signing period due to his impressive bat. However, because he's still just 17 years old, there's a long way to go in his development and he's far from a sure thing. If he produces to the degree that his tools allow, then he'll be a fine player. But many a top international prospect has hit major bumps along the road, and it will be a while before we know if Tatis will be able to play in the big leagues.

On the whole, the White Sox did quite well for themselves here. Shields, for all his woes and inconsistency of late, is nevertheless a fine enough pitcher. He isn't the quasi-ace that he once was with the Rays, but the White Sox don't need an ace. They already have Sale, and Quintana has been very good as well. They simply need quality innings. Shields can provide that, and anything else that he gives them is gravy. The huge lump of money included in the deal makes him a fairly cheap option too.

Losing Johnson means that their starting depth remains static and thin for the time being. Carson Fulmer is currently at Double-A and may very well become an option before the end of the season, but it's too soon to tell. If Latos can be transitioned into a long relief role, it will make life slightly easier in the immediate future. There's also still plenty of time left for the Sox to trade for more depth.

For the Padres, the move represents a way to clear off a roster spot and a bit of salary. Johnson and Tatis aren't phenomenal gets, but they're still intriguing pieces if nothing else. Johnson's future is murky at the moment, and Tatis is a long project. But they're still two more players that San Diego has to tinker with, and represent one fewer aging starter on a slightly unwieldy contract.

Neither team got markedly better here. This isn't a Samardzija + Hammel for Russell + McKinney kind of deal. It's not David Price going to the Tigers, or David Price going to the Blue Jays.

It's the White Sox shoring up an area of need and the Padres starting to sell off more pieces after their fool's errand of an offseason a year and a half ago. It was apparent from the beginning that Shields wasn't the answer in San Diego. Perhaps he is now in Chicago.

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Nicolas Stellini is a featured writer at Beyond the Box Score. He also writes for Baseball Prospectus and BP Bronx. You can follow him on Twitter at @StelliniTweets.