I would venture a guess that you both are using Abuyamang as a poacher and relying on through balls and pace to score goals - whereas after one successful season (even as one of the best teams in the league) - other teams will always start playing deeper against you.
At least that would explain why Abuyamang doesn't score and one of your wingers does. Try playing with two strikers for a bit, or maybe three - mixing it up a little.