Goal differential and making the MLS Playoffs

Note: This chart originally appeared on BrotherlyGame for a Philadelphia Union preview but I thought this community might like to see the relationship between goals and making the playoffs.

We know the league's proud tradition of parity, but did you ever think that a mere four goals could increase a team's chances of making the playoffs by 75%? That apparently has been the case over the last four MLS seasons. The chart below shows the relationship between goals scored, goals conceded and probability of making the playoffs. 

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If a team's goal differential is below -6 (red triangle) there is no chance of making the playoffs, or at least it's a low enough probability that we haven't witnessed it yet. Playoff chances are just 13% between -3 and -6 (yellow band). No team has made the playoffs when allowing 58 or more goals either. But things start looking up after that. 57% of the teams make the playoffs with a goal difference between -2 and 0 (orange band). And if a team can grab just a slim one goal advantage they're basically a lock at 83% (blue band). Not surprisingly, teams with a goal difference of 10 or more have never failed to qualify (green triangle).  

The relationship between goals scored and conceded is also worth noting. While the Rsquared is just 10%, there is a correlation between scoring goals and not conceding them. It seems that success is a bit of a spiral staircase then, where scoring goals aligns with not conceding them and vice versa. But if your team happens to be mired in that dreaded middle, it appears a goal here or a smile from lady luck there might be the difference between a long offseason and a postseason run.