The Los Angeles Dodgers (18-10) are top the NL West, but they might not be able to rely on their early success because the starting rotation is in shambles. Beyond Clayton Kershaw and Zack Greinke the club doesn't have much.

Hyun-Jin Ryu has yet to pitch this season because he's been dealing with shoulder inflammation. He was shut down during spring training and began progressing in his rehab lately as the team expected him to return to the rotation in June. However, he's suffered a setback and now the trade rumors will once again resurface for Los Angeles, who has already lost Brandon McCarthy to Tommy John surgery.

"Hyun-Jin Ryu appears no closer to the big-league mound, and in fact seems quite a ways away from returning to it," writes Jon Heyman of CBS Sports. "While no major structural damage has been seen in multiple MRIs, it's possible there's a fraying of the labrum, which may not show up on such a diagnostic test. Ryu has felt an irritation whenever he's gone to throw, and while there's no labrum tear diagnosed and no reason to believe the injury is serious, a shoulder/labrum cleanup can't be ruled out at this point. Manager Don Mattingly conceded Wednesday night Ryu's been 'slowed a bit' in his return efforts."

"The Dodgers' summer trade plans could hinge in large part on Ryu's health," adds Jeff Todd of MLBTradeRumors.com.

President of baseball operations Andrew Friedman acknowledged that the club will look to solve the rotation issues internally on a turn-by-turn basis because big trades probably won't begin to occur until June or July. He did not rule out making a deal for another starter, and those possible trade talks have likely increased with growing speculation that Greinke will opt out of his contract once the season ends.

So here are the candidates the club might consider.

Cole Hamels - We already know the story with him. General manager Ruben Amaro wants an excessive return for the left-hander, who is owed $96 million over the next four seasons. The Dodgers have the prospects to make a deal happen, but they've previously reiterated Joc Pederson, Julio Urias and Corey Seager are untouchable. Perhaps Amaro lowers his demands as the trade deadline gets extremely close because he will need to get rid of Hamels before July 31.

Johnny Cueto - Sources have said they expect the Dodgers to make a run at the Cincinnati Reds' right-hander, who is expected to command a $200 million contract once the season ends. It's a likely possibility the Reds fall behind in the competitive NL Central and look to deal Cueto because they will not be able to afford him once he hits the free-agent market. However, if the Dodgers make this move, they'll be faced with investing a ton of money in their starting rotation with Cueto and Greinke (if he opts out), or letting one of them walk at the end of the year.

Jordan Zimmermann - The two-time All-Star is off to a slow start in 2015 (2-2 with a 4.15 ERA), but he'll likely return to form sooner rather than later. He'll also hit free agency at the end of the season and the Nationals have failed to sign him to a contract extension on multiple occasions. It's pretty clear he won't remain in Washington beyond 2015, so the Nats might seek to get value in return for the right-hander considering they have prospects Lucas Giolito and A.J. Cole as well as reliever Tanner Roark ready to slide into the rotation if need be.

Scott Kazmir - The left-hander is off to a great start this season with the Oakland Athletics and it's more than likely general manager Billy Beane will look to trade him because the club won't be able to afford him once he hits free agency in the fall. Kazmir pitched for the Rays when Friedman was running the show in Tampa Bay, so a reunion at the trade deadline wouldn't be surprising. He'll also be much cheaper (in terms of trade value) than the aforementioned options, and if the Dodgers remain hesitant with giving up their better prospects, this could be their best option.

"[The Dodgers have] managed to go 3-3 in the six previous starts by pitchers who weren't supposed to be in the rotation, but there is no way they can count on even that mediocrity continuing," writes Steve Dilbeck of the Los Angeles Times. "Should they make it to the playoffs, they're going to need a reliable No. 3 starter. And right now, they have Kershaw and Greinke and a lot of trouble."

As we get closer to the trade deadline, the Dodgers' plans will become more transparent.