The first big trade of the season was made Saturday afternoon. The Padres shipped veteran right-hander James Shields to the White Sox for prospect Fernando Tatis Jr. and righty Erik Johnson. San Diego is also covering $30 million of the $56 million still owed to Shields. The Shields era was a disaster for the Padres.

Last offseason, the Padres went all-in hoping to contend in the NL West, but it didn't happen, and now GM A.J. Preller is picking up the pieces. Ian Kennedy and Justin Upton were allowed to leave as free agents, and both Craig Kimbrel and Joaquin Benoit were traded away over the winter. Now Shields has been dealt.

Which Padre could be the next to go? Here are the leading candidates.

Fernando Rodney and Derek Norris could be the next Padres to be traded. USATSI

RHP Andrew Cashner

These players are listed alphabetically, but it is fitting we start with Cashner, who is a prime piece of trade bait. He's going to be a free agent after the season, and power arms are always in high demand. Cashner, 29, recently returned from a minor hamstring injury and has a 4.79 ERA (80 ERA+) in 47 innings this season.

Even though he's continued to be more potential than production, guys who consistently run their fastball into the mid-90s like Cashner always have suitors. San Diego could keep him and make him the qualifying offer after the season -- that's what the Padres did with Kennedy last year -- though I think Cashner's trade value is greater than the value of a supplemental first-round pick. Chances of being traded: High

OF Matt Kemp

The Padres reportedly tried to trade Kemp over the winter, and I'm certain they would happily move him today if it were possible. He's hitting .240/.249/476 (95 OPS+) this season, he's a defensively liability, he's owed roughly $67 million through 2019, and he has an arthritic condition in his hips. Lots and lots of red flags here. The only suitors figure to be AL teams willing to use Kemp as a full-time DH. Chances of being traded: Low

C Derek Norris

The offensive bar for catchers is quite low, so while Norris' .198/.258/.346 (66 OPS+) batting line this season is an eyesore, he did hit .256/.333/.405 (108 OPS+) from 2013-15. Teams are going to look at him as a bounce-back candidate at age 27, not someone in decline. Norris has thrown out 34 percent of would-be base-stealers the last two years, and StatCorner rates him as an above-average pitch-framer, so he offers defensive value if nothing else. The Padres have some catching depth (Christian Bethancourt, Austin Hedges), making Norris a very tradeable commodity. Chances of being traded: Moderate

LHP Drew Pomeranz

The Padres picked up Pomeranz in a trade with the Athletics over the winter, and he's taken advantage of the opportunity to return to the rotation. So far this season he has a 2.22 ERA (173 ERA+) with 77 strikeouts in 65 innings. Pomeranz, 27, always had good stuff. The problem has been staying on the field. He's had a lot of injury problems over the years.

That said, Pomeranz is under team control through 2018, so the Padres could opt to keep him and build their rotation around him. The alternative is capitalizing on his suddenly sky-high trade value before he gets hurt again. You can make a strong argument for trading or keeping Pomeranz. I'm not sure there's a right answer here. Chances of being traded: Moderate

RHP Fernando Rodney

Rodney is exactly the type of player a rebuilding team should move. He's 39 years old, he's having a phenomenal year (0.00 ERA with 10 saves in 20 innings), and he's on a one-year contract. Why in the world would the Padres keep him? To try to win 78 games instead of 74? It makes no sense, especially with relievers always in demand. Chances of being traded: High

RHP Tyson Ross

In a vacuum, the Padres do not have a more valuable trade chip than Ross. He has a 3.16 ERA (111 ERA+) with 531 strikeouts in 522 innings since arriving in San Diego four years ago. Ross is only 29 and he's under team control as an arbitration-eligible player in 2017 too. The Padres could get a haul for their ace.

The problem? Ross has not pitched since Opening Day due to shoulder inflammation, and he only just recently started a throwing program. He's not particularly close to returning. Players can be traded while injured, but I have a hard time thinking clubs will be willing to pay top dollar for a pitcher out with an arm injury. The best move for the Padres is waiting for Ross to return and letting him show teams he's healthy, then move him in the offseason. Chances of being traded (at the deadline): Low

IF Yangervis Solarte

Solarte returned from a hamstring injury not too long ago and he's hitting .323/.417/.565 (169 OPS+) in 18 games around the injury. Last year he put up a .270/.320/.428 (109 OPS+) batting line in almost 600 plate appearances, so he's shown he can hack at the MLB level after spending much of his career bouncing around Triple-A.

Here are the nuts and bolts: Solarte is 28, he's cheap and under team control through 2019, he's a switch-hitter who can provide offense, and he can play all over the infield as well as some outfield. That's a really valuable player. A player who might be worth keeping around. Solarte figures to generate a ton of interest, and it would be foolish for the Padres to not at least listen. Chances of being traded: Moderate

OF Melvin Upton Jr.

After two disastrous years with the Braves, Upton has found a home with the Padres, hitting .253/.319/.409 (103 OPS+) since the start of the last season. That includes a .247/.311/.389 (93 OPS+) line this year. Upton's not really a center fielder anymore, but he can fill in there if necessary. He's more of a left fielder at this point.

The Padres ate a ton of money to move Shields, and they'd have to eat a ton of money to move Upton too. He's owed $27 million through the end of next season. Fair or not, I think teams are going to be a little scared off by Upton. He was terrible in Atlanta and his brother Justin has been pretty bad with the Tigers so far this year. There might be an Upton stigma. No one wants to pick him up and have him turn into a pumpkin. Injuries could always force someone's hand though. Chances of being traded: Low

The Padres went all-in last year and tried to win. It didn't work, and now Preller is trying to rebuild. The Shields trade was the latest step.

Rodney seems like the obvious candidate to go next, and Cashner figures to be right behind him. After that, it becomes a question of how quickly the Padres want to part with Pomeranz, Solarte, Norris, and Ross.