We used a temporal model to capture the fact that teams scoring lots of goals for a game, will likely be scoring lots of goals for the next ones. This example shows the enormous complications of predicting sports events: they are impacted by psychological factors, the exact team composition, the styles of both teams, the strategy designed by the manager, and even the weather. Some of these variables can be collected, and some of them are just impossible to get. 

The final complication is that we can never have too many observations, since sports seasons are limited, and each season implies very different team dynamics.