Everyone remembers the name that took fantasy baseball by storm in 2012: Mike Trout. While his breakout season was epic, every year there are rookies who burst onto the scene from relative obscurity. They may be kids, but every year they’re making more and more of an impact on both major league teams and fantasy owners alike. These diamonds in the rough can provide a huge lift to your team, and today we’re going to examine a few of these first year difference makers.

Evan Gattis ATL | C

With Brian McCann out the first month of the season, the Braves could either hand the reins to Gerald Laird, or give the rookie Gattis a shot. The former janitor, ski-lift operator, and pizza boy took the job and ran with it, all the way to Rookie of the Month honors for April. He’s not a batting average guy, but from the C slot he’s slugged 7 HR and driven in 19 already. McCann has returned, but Atlanta has been playing Gattis in the outfield to get his bat in the lineup – positional flexibility for your fantasy lineup is not far off.

Jose Fernandez MIA | SP

After a rash of injuries beset the Marlins ‘starting rotation’, Fernandez was called up early and debuted on April 7th. All he did was strike out 8 Mets in 5 innings, allowing one run, and becoming the first waiver wire instant addition of 2013. Fernandez then went on to allow 9 earned runs over his next 15 innings, leading many to give him the boot. Give Jose another strong look, however. Despite playing in the sinkhole that is Miami, over his last two outings he’s given up just two earned runs over 11 innings, while striking out 13. The kid has big league stuff and is a great low-risk addition to almost any team.

Hyun-Jin Ryu LAD | SP

He may look more like a professional hotdog eater than a major league starting pitcher, but Ryu has made his presence felt in the Dodgers’ rotation this season. With Zach Greinke out, the rest of the LA rotation read like this: Beckett, Lilly, Capuano. A lift was needed, and Ryu has been the man. He’s spun quality starts in 5 of 7 outings so far and provided 48 K in 43 innings pitched. As the Dodgers get healthy and begin to click, Ryu’s value will rise. He’s an excellent #4 or #5 starter for any team, with room to grow.

Nolan Arenado COL | 3B

Widely considered the top hitting prospect in the Rockies organization, Arenado was not called up until April 28th to keep his service time down. Since then, all he’s done is rake, and if he’s unowned in your league, it’s time to pay attention. He’s homered three times in 34 at bats, including a grand slam off David Price on May 4th. He’s batted all over the Rockies potent lineup, and has settled in the top half, where he will have ample opportunities to produce runs and RBI. It doesn’t hurt that he’ll play half his games in the thin Colorado air. Arenado looks like a rookie to hold on to for the balance of 2013.

Jedd Gyorko SD | 2B, 3B

The fantasy community made much of Gyorko during draft season, including yours truly advising many to be sure to pick him up in the later rounds or off the wire. Well, I looked pretty stupid for the first month, as on April 29th, Jedd was batting .236 with 0 home runs and an OBP of .303 – simply dreadful. Since that time, everything has clicked for the Padres infielder. He’s hit 3 home runs, driven in 6, and raised his average to .271. With his multi-positional eligibility, improved batting eye, and surging Padres lineup around him, Gyorko is worth at least a speculative add in almost all formats.

Marcell Ozuna MIA | OF

They say when you have nothing you have nothing to lose. This aptly describes the Miami Marlins this season. They have thrown caution to the wind in the absence of Giancarlo Stanton in their search for power, and thus Marcell Ozuna finds himself in the bigs despite his lack of a single at-bat at the AAA level. He’s shown power in the minors and more or less raked at all levels, and Marcell isn’t worried about his lack of experience – he’s come out of the gates at a .419 clip, and has quickly moved to the top-middle of the thin Marlins lineup. He passes the eye test too, not looking overwhelmed or swinging at pitches way out of the zone. Deep leaguers would do well to make room for Ozuna on their teams, and mixed leaguers should definitely be watching as well.

Oswaldo Arcia MIN | OF

Arcia has come into the fantasy spotlight over the past two weeks after batting .400 with a homer, 7 runs scored, and 6 RBI. He’s hitting toward the bottom of the Twins lineup, but is progressing quickly and should move up soon. He batted .393/.474/.727 at AAA, which earned him a call up just shy of his 22nd birthday. He’s basically available in all leagues, and profiles as a potential high batting average fourth outfielder. If you’re playing in a deeper format, make room for Oswaldo.

Didi Gregorious AZ | SS

2013 may just be the year of the budget shortstop, and Gregorious is leading the charge. He came from nowhere to post a .338 AVG and .434 OBP thus far, and can be found hitting out of the 2-hole in the powerful Diamondbacks lineup. The sample size is small so far (only 49 total AB as of 5/11) but he crushed the ball in AAA before being called up, and the batting situation in Arizona is ideal. He’s available in more than 75% of leagues right now, and if you drafted Reyes, Hanley, Aybar, or want to give Rollins or Prado a night off, consider Gregorious.