Robbie Erlin was called up to start against the Phillies last Wednesday and pitched very well. He'll hold plenty of value in NL-only leagues the rest of the way. He's a left-handed control specialist with average strikeout potential, similar to Tommy Milone. Don't start him this Tuesday at the Red Sox though.
John Hellweg was called up by the Brewers last night to start against the Pirates and he let up 5 ER in 1 2/3 IP. I'm not sure if Hellweg will get another start but I wouldn't pick him up in any format. His 2.82 ERA at AAA is extremely misleading. He has battled major command problems throughout his minor league career. He had 44 BB and 50 K in 76 2/3 IP at AAA. His FIP was 4.48 there and his .240 BABIP is likely what led to his ERA being so low.
Drew Pomeranz was called up by the Rockies to take Juan Nicasio's spot in the rotation and should hold decent NL-only value while pitching away from Coors. You'll want to be careful with the matchups while he's at home.
Brian Bogusevic was called up by the Cubs and should get regular playing time in their outfield with David DeJesus likely out until after the all-star break. He was hitting .346 with 7 HR, 14 SB, and a 1.002 OPS against RHP at AAA.
Taylor Jordan will replace Dan Haren in the Nationals rotation for the time being. He'll face the Brewers next week and was dominant at AA this season. While I don't think he has frontline starter potential he has great control and command of his pitches and should be solid.
J.J. Putz was activated today and will likely take over as closer after 1 or 2 successful outings. Heath Bell is worth hanging onto just in case Putz has any more arm issues.
Everth Cabrera is likely to make his return next weekend. He went on the DL with a hamstring injury so it will be interested to see if that affects his SB total for the next few weeks.
Wandy Rodriguez is expected to be out until after the all-star break due to lingering pain in his throwing arm.
Ted Lilly should be back in the Dodger's rotation around the all-star break.
Brandon Beachy has a shot to join the Braves rotation in about a month if he proves to be healthy. I think he is more valuable of a DL or bench spot in H2H leagues due to his potential to really make an impact in September if you're already on pace to make the playoffs.
Evan Gattis could be out until after the all-star break with his oblique injury.
Corey Hart needs another knee surgery and will not return this season. He'll be a prime buy-low candidate for 2014.
Ryan Vogelsong should be healthy enough to return by August and, despite his rough start to the season, he has the ability to be a difference-maker in NL-only leagues.