He needs to play with players who have decent offensive talent and can play a posession/cycle game. The only two wingers on the team who fit that description are Patches and Gallagher.
Briere and Galchenyuk (for now) are too easily knocked off the puck. Bourque is a complete disaster. Pust and Moen have little offensive talent.
If we could pick up a big two-way winger like Jenner or Berglund to play beside Eller, I'm sure we'd see his production increase and it would finally give us a line that can match up with some of the bigger lines out there that always seem to kill us. ie. Malkin/Neal, Schenn/Simmonds, Getzlaf/Perry, Kopitar/Brown, Thornton/Burns, Steen/Backes/Oshie etc.
For now, I'm willing to bet reuniting him with Gallagher will be a good spark.