Yaya Sanogo started Arsenal's first two matches of the season, against Manchester City in the Community Shield and against Crystal Palace in the Premier League. Since then, he's only started three games, against Leicester, Borussia Dortmund, and Galatasaray, and despite scoring his first Arsenal goal against Dortmund, he's still the 4th or 5th choice centre forward, behind Olivier Giroud, Danny Welbeck, Alexis and possibly Theo Walcott.
Sanogo, though, is still only 21, and has quite a lot of raw potential. Thus, this tweet, from David Ornstein, makes sense:
Sanogo to leave Arsenal on loan in Jan. Another PL club most likely. #AFC want him to get game time & confidence. 1 goal in 19 since joining— David Ornstein (@bbcsport_david) December 19, 2014
At this stage, Sanogo isn't really needed by Arsenal. A loan, though, for a club that'd use his strengths, where his main task isn't necessarily to score goals, would be incredibly beneficial. Of course, scoring goals would be good too, but if Sanogo goes to a club where he's expected to just score goals, it won't end well for him. If he were to end up at either Crystal Palace or QPR, two clubs that utilise systems where a big target-man striker is not the goal-getter, it would be good for them, good for Sanogo, and good for Arsenal.