All of the forwards (Aguero, Iheanacho, even Sterling) need to follow in on the goal rather than stop and wait for the pull back. When Aguero made his run in the second half, Iheanacho followed him so far but then stalled- either waiting for the pull back or because he thought Aguero would never pass. Had he continued his run at full speed he may just have arrived in time to score. It's something we've been guilty of for a number of seasons, and I often wonder if it stems from the training ground.