Board Thread:Misc./@comment-26875950-20150810164018/@comment-25232661-20150812045441

That was the aptitude test - that was just to make sure they could keep their balance in the harness and stay upright. During their actual training Shadis said that Eren had "no particular talent aside from his excellent close combat skills but slowly but steadily improved his grades through outstanding effort".

One of Eren's main character traits in the beginning of the manga was that he didn't give up, but kept trying until he improved and succeeded - like staying upright for a few seconds during the aptitude test even though his belt was faulty.

I think that makes it all the more exceptional that Eren graduated 5th, considering that all four of the people who graduated above him had some added advantage - Mikasa being super strong and the other three being shifters & having been trained from a much earlier age than the others.