Measuring success is not always the easiest thing to do in life. What can be seen as a success to one person, could look like total failure to another. Different goals and different expectations bring on different verdicts. In the NFL, defining success is rather simple.
The Cowboys, just like all NFL teams, want to score points on offense and stop teams from scoring on defense. At their core, sports are a simple concept. So it stands to reason, the plays that increase an offense’s chances of scoring are deemed successful and the plays that reduce the scoring probability are labeled unsuccessful (and then the inverse of that to assess defensive performance, play to play).
From this perspective, success rate is born. Plays that increase scoring probability are defined as “successful” and the frequency of these plays is the “success rate.”
The degree in which a play is successful is measured by expected points added (or EPA). Positive EPAs are successful plays and negative EPAs are unsuccessful plays. Large EPA numbers indicate big plays that changed scoring probability while small EPA numbers indicate lesser plays that increased scoring probability.
Why does all of this matter?
It’s important to know what’s working and what’s not working. And right now, first down runs are NOT working for the Dallas Cowboys.