Here are three players with low ownership rates who could pay immediate dividends in fantasy leagues:
Mike Aviles, Kansas City Royals (owned in 7% of Yahoo! leagues)
In 592 lifetime PA in the majors, Aviles has a .298-13-61-83-9 fantasy line which is outstanding production for a guy to slot in your MI position. Of course, the problem is that Aviles toils for the Royals, who think he fits in behind both Yuniesky Betancourt and Chris Getz in the pecking order and sent him to the minors early in the year. But Aviles has started five of the past six games (and pinch-hit in the other). Eventually talent wins out so expect Aviles to log more playing time than either of those inferior players for the remainder of the season.
Scott Hairston, San Diego Padres (owned in 3% of Yahoo! leagues)
Despite his great production for half a season for the Padres in 2009, Hairston opened the year as a platoon player and was in the lesser half as the right-handed part of the time share with Tony Gwynn Jr. But he has started 10 games since April 28th and has a .294 AVG with 4 HR in that span. RoS ZiPS gives him 14 HR in 337 ABs. If he can stay healthy, Hairston has a chance to exceed that playing time prediction. He can offer a nice power/speed combo but Hairston will need to cut back on his strikeouts, which currently sits at a 35.8 K%, if he wants to improve on his .254 AVG.
Scott Olsen, Washington Nationals (owned in 5% of Yahoo! leagues)
After getting lit up in his first two outings of the season, Olsen is 2-0 in his last three starts, with a 0.44 ERA. Additionally, he has 5 BB and 20 Ks in 20.1 IP in that stretch. Olsen has a little extra zip on his fastball this year, with his average velocity of 89.2 mph a full 1.2 mph higher than it was a year ago. That, along with throwing his fastball less often, has helped make a very poor pitch in 2009 (-17.8 wFB) one that is almost league average (-1.4 wFB) this year. Olsen has been throwing both his slider and change more often in 2010. His slider is a very good pitch and his change is now a plus offering.