Jordan Walden could return as soon as next weekend. Brandon Beachy should return in late June from Tommy John surgery, possibly resulting in Julio Teheran getting sent down. It's quite encouraging that Evan Gattis has been an effective pinch hitter and when he does start is making the most of it. Eric O'Flaherty had Tommy John surgery and will miss the rest of the season.
Jim Henderson injured his hamstring last night and there's a chance he will be placed on the DL and miss at least a couple weeks. Francisco Rodriguez got the save last night after Henderson was removed and seems to be the best option to fill in as closer. Mike Fiers is starting for Kyle Lohse today because Lohse's elbow is sore. This could lead to a more serious diagnosis for Lohse down the line but for now there aren't many details.
Chris Carpenter has been throwing bullpen sessions and might be an option for the rotation or bullpen in about a month or so. He's a high risk to suffer a setback at any point so I wouldn't invest too heavily in him. Jake Westbrook isn't close to returning yet and it wouldn't surprise me if his elbow issue ends up being serious. Tyler Lyons was called up and pitched extremely well against the Padres. He's worth a flier if you really need starting pitching help but I wouldn't expect him to be a real impact guy. Jaime Garcia will likely undergo shoulder surgery and miss the rest of the season. With Westbrook and Garcia sidelined I think right now is the time to pick up Michael Wacha in NL-only or deep leagues. In mixed leagues you can wait until you hear more buzz about his call-up but I think it's only a matter of time and that he'll be productive right away this season.
Carlos Villanueva has been moved to the bullpen due to Matt Garza's return. It's likely that the team trades Garza at some point so if you should stash Villanueva in NL-only leagues if you have the roster space.
Adam Eaton has experienced a setback and will probably miss about another month. Aaron Hill is looking at a mid-June return at best from his broken hand. Heath Bell is doing well in the closer role and I think he's worth trying to trade for. Many are skeptical of Bell's success thus far but his FIP, xFIP, and SIERA are all under 3 while he has actually been unlucky with a .400 BABIP. Putz is nowhere near returning and I don't think that David Hernandez getting the job at some point is a given.
Hanley Ramirez should return within a couple weeks. Dee Gordon will likely be sent down upon Ramirez' return. Josh Beckett could return from his groin injury within a couple weeks. The closer situation is a bit unclear but I think Kenley Jansen will have the job soon enough.
Santiago Casilla will likely undergo knee surgery and be out until at least July. Ryan Vogelsong will be out a couple months with a broken hand and it's unclear who will replace him in the rotation. Keep an eye on this situation.
Nathan Eovaldi could be just 2-3 weeks away from returning to the rotation. He'll be a decent NL-only option when he gets back. Logan Morrison is a week or two away from returning and likely becoming the team's everyday first baseman. He'll likely hit in the middle of the order and is worth a look in all formats. Giancarlo Stanton should return in a couple weeks as well.
Ike Davis is likely to be sent down after this weekend. He is completely lost at the plate right now. Davis is the ultimate buy-low candidate and I still believe he will turn things around at some point. If he gets dropped in your league or you can trade for him cheaply then you know what to do. Zack Wheeler should be called up within 2-3 weeks and should be owned in all formats as long as you have a roster spot for him. He could make an impact similar to what Matt Harvey did last season. Rafael Montero was promoted to AAA and likely won't be too far behind Wheeler in being called up.
Danny Espinosa has been playing with a fractured wrist and could end up needing surgery at some point. There's also a chance that he will continue to play through the injury and struggle at the plate for much of the season. Steve Lombardozzi and Jeff Kobernus will fill in for now but Anthony Rendon could eventually be called up to play second base.
Burch Smith was sent back down the minors while Tim Stauffer was impressive in relief of Smith in his last start. Stauffer might get a shot in the rotation at some point but it's likely Clayton Richard will return this Monday. Cameron Maybin is about week away from returning.
Mike Adams will return tomorrow and should be a top holds option as long as he can stay healthy. Carlos Zambrano has been pitching well and could eventually be an option to replace Jon Pettibone if he struggles. John Lannan is just a couple weeks from returning. Tyler Cloyd and Jon Pettibone's rotation spots are anything but guaranteed and I would express caution when investing in one of them.
Jeff Karstens has been shut down after experiencing a setback. Francisco Liriano has been extremely impressive thus far in his first year in the NL. Call me crazy but I think he's worth a pickup in all formats.
Sean Marshall was placed on the DL with a recurring shoulder issue. Nobody is really providing an impact replacing Ryan Ludwick although Chris Heisey will return in a couple weeks. It wouldn't surprise me if the Reds decide that Billy Hamilton gives them the best chance for both offensive and defensive impact out of all their options to replace Ludwick and call him up soon.
Roy Oswalt is likely a couple weeks from joining the Rockies rotation. I really like his chances of producing well in the NL West, especially in his road starts. Rafael Betancourt should be back within a couple days but it's noteworthy that Rex Brothers filled in for him as closer. With Betancourt a likely candidate to be traded around the deadline, Brothers is worth owning for owners who want to speculate on saves. Jeff Francis might not have a rotation spot to return to with Oswalt on his way and Tyler Chatwood pitching well.