If you are in need of second base help for a deep league or NL-only league then pay attention to Scooter Gennett of the Brewers. He is sharing time at second base with Rickie Weeks right now but if he gets hot it will be difficult to keep him out of the lineup. Gennett doesn't have great power/speed but he can hit for average and provide a handful of HR and 10+ SB if he sticks on the roster for the rest of the season.
Caleb Gindl has been called up to replace Ryan Braun and could potentially hold some value over the next couple weeks against RHP. He was hitting .292 with 7 HR against RHP at AAA.
Zack Wheeler will make his MLB debut next Tuesday against the Braves and it worth owning in all formats. He can make the type of impact that Matt Harvey did last season.
Josh Rutledge will replace Troy Tulowitzki as the Rockies shortstop until late July. He's worth a pickup in all formats if you need a shortstop or MI with some power.
Brandon Cumpton will start today against the Dodgers, replacing AJ Burnett in the rotation. I don't think he'll have much fantasy value moving forward and wouldn't pick him up right now unless you are really desperate. Cumpton isn't highly regarded as a prospect.
Ryan Braun was finally placed on the DL with his thumb injury but should be back within 15 days from the retroactive filing date of June 9th. Hopefully the thumb will heal and won't affect him after he returns but you never know for sure with these types of injuries. Still, I wouldn't worry about him and am not downgrading his value over an injury like this. He's hitting .304 with 9 HR on the year and has played through the thumb injury for a while.
Corey Hart might not be back until late July. There's no new injury but he's still trying to get his knee as close to 100% as possible. I still think he's worth hanging on to if you have the DL spot or bench space.
Aaron Hill should be able to return next weekend. Eric Chavez is also on his way back but when Hill is playing every day and Prado is at 3B it will be difficult for Chavez to find many starts.
JJ Putz will begin a rehab assignment early next week. It's certainly possible that he returns to full health and has a successful rest of the season as the Diamondbacks closer but it's far from a guarantee. Heath Bell has pitched very well in place of Putz but may move into a setup role upon Putz' return if Putz proves he is back at 100%.
Chris Capuano will be back next week and will face-off against the Yankees.
Marco Scutaro is dealing with a pinkie injury but should avoid the DL and return early next week. Pay close attention to his hitting when he returns because this injury could affect it.
Pablo Sandoval should be back when he's first eligible to come off the DL. His foot injury is minor.
Logan Morrison just came off the DL from a knee injury and now is dealing with a back issue. It remains to be seen whether this will force him back onto the DL. For what it's worth, Morrison has hit well in the three games he has played.
Nathan Eovaldi will make his first start of the season next week against the Diamondbacks. I would play the matchups with Eovaldi and wouldn't start him in his first game back.
Bryce Harper might be back by the end of the month depending on how his knee responds to increased activity. Danny Espinosa could return in about a week but it remains to be seen if his wrist will still affect his hitting. Wilson Ramos should return sometime in July from his hamstring injury.
Jedd Gyorko will be out for a couple weeks and Logan Forsythe is worth a pickup as his replacement as the starter at second base while he's out. Yonder Alonso still should be back by early July.
John Lannan will return on Monday against his former team, the Nationals. Lannan is only worth playing in the most favorable of matchups and the Nationals just aren't one of them.
Carlos Ruiz should be back in 1-2 weeks. He had a big year last season but it's questionable whether he can even come close to repeating that performance for the rest of this season.
A.J. Burnett could be out until late July with his calf injury.
Starling Marte is dealing with a rib injury but should be able to avoid the DL. Alex Presley has been replacing him in the leadoff spot and the outfield.
Johnny Cueto will return Sunday against the Brewers. Tony Cingrani will be sent back down to AAA but he's definitely worth stashing for his fantasy impact should the Reds need to call him back up at some point. Obviously this depends on your amount of bench space.
Troy Tulowitzki will be out until late July with a broken rib.
Roy Oswalt should join the Rockies rotation next week and I think he's worth a pickup in any league. He's been pitching very well in the minors. Oswalt might be overlooked by some due to his 5.8 ERA with the Rangers last season but he was extremely unlucky. His xFIP and SIERA were 3.27 and 3.17 respectively while his BABIP against was .378.
Michael Wacha was sent down by the Cardinals. This is terrible news for anyone who invested heavily in him after his call-up but he should be back at some point so he's definitely worth hanging on to if you have the space.
Kenley Jansen has taken over as the Dodgers closer and should excel in the role. Brandon League will likely pitch the 7th or 8th inning and will be valuable in holds leagues.
Huston Street returned from the DL and should be fine moving forward. As Ray mentioned in his recent closer article, Street is a trade candidate so Luke Gregerson is definitely worth hanging on to. http://www.faketeams.com/2013/6/13/4425994/five-relievers-who-could-be-closing-by-july-31st
Charlie Morton made his return and pitched well. He's worth a pickup and should be useful in NL-only leagues with the right matchup.