I'm taking a look at 5 outfielders whose increase in playing time warrants their consideration to your fantasy roster. While you probably don't want them as one of your starters, these guys will provide some quality depth as fourth, fifth, or even sixth outfielders, depending upon your league.
John Mayberry Jr. - Phillies LF
After a season where Mayberry continued to feast on LHP, (2011 - .306 avg., .595 slg)(career - .299, .604) Charlie Manuel and Ruben Amaro Jr. will probably give him the majority of playing time in LF for at least 2012. The Phillies have let it be known they want Dominic Brown in AAA for "more seasoning". At the major league level, newly acquired Lance Nix will steal some at-bats versus some righties. Mayberry has added value as he qualifies as a CF, and in some leagues as a RF as well. A small downside for Mayberry is that his average for home/road splits is wide (Career BA - .296/ .237), but at least his power has not been affected (Career SLG - .522/ .514). With consistent playing time, I wouldn't be surprised with 25-30 HR's.
Now that Yonder Alonso has been traded to the San Diego Padres in the Matt Latos trade, LF is open for the Reds. As long as Walt Jocketty doesn't go get a LF, Heisey should get first crack. Heisey showed some pop last year with 18 HR and a .487 SLG. He hits righties very well (Career - .288 avg, .539 slg), but lefties poorly (.180, .300). Todd Frazier may get some at-bats versus lefties, but it should be Heisey's job to lose.
Now that Magglio Ordonez is no longer in Detroit, Boesch will try to take over right field full time. So far in his short career, Boesch has displayed a troubling tendency in his splits. No, it's not the lefty/righty split. Nor is it the home/road split. His problem is the first half/second half split. In both his years he has started out on fire (.321 avg., .535 slg), only to turn frigid in the latter half of the year (.182, .272). While he did miss the last month of the season due to ligament damage to his thumb, his numbers have tended to decline after June. With no real competition to speak of, he should get a chance to turn the tables on his second half swoons. He could put up some quality numbers if he can just be consistent.
Seen by some as a throw-in in the Andrew Bailey trade, the Red Sox see Sweeney as their starting RF in 2012. Depending on your league, he can qualify at all outfield positions this year. Sweeney should benefit from switching home fields, and for being in a much more potent lineup. While he will definitely lose some starts to Darnell McDonald against southpaws, Sweeney will get the majority of starts in RF this year. He's not a power guy by any means, but he could easily hit .300 this year.
After having a disappointing 2010 season due to surgery on his Achilies the previous season, Reimold had a decent second half in 2011 to put him in line for a starting job in 2012. The O's signed Endy Chavez to be a backup to all outfield spots, leaving Reimold with an opportunity some thought would never come again in an O's uniform. He has decent pop and with a full time gig can hit 20-25 homers.