Conversion percentage refers to the amount of times an offense reaches the line to gain on any given down. Additionally, conversion percentage may be used for how many times a team successfully converts an extra point or two-point conversion.
2nd down conversion percentages are key for determining success of playcalling. 2nd down is often where offensive and defensive coordinators can be the most creative when drawing up plays, because there is not as much yardage to gain and the offense is guaranteed at least another play if they don't turn the ball over.
3rd downs are key for both teams because both the offense and defense have the most to lose. 3rd down conversion percentages can be used to determine which teams perform under pressure. Converting a 3rd down is a sigh of relief for an offense, but stopping one is a big victory for a defense.
4th down conversions are special because they imply the offense is "going for it"-that is, attempting to reach the line to gain instead of punting the ball away to establish better field position. Teams with high 4th down conversion percentages are considered more "clutch" because they reached the line to gain when the most was at stake.
Extra points are usually expected to be converted. Every collegiate and professional team should have a high extra point conversion percentage. A team with a low PAT conversion rate either needs to reconnect with the fundamentals of the game or find a better kicker.
Two-point conversions are not nearly as common as extra points, but their percentages are a good indicator of how a team performs in short-yardage situations. Why Conversion Percentages are Important
Journalists, fans, coaches, and analysts use conversion percentages to determine which teams do well on which downs. Trends among certain teams and downs may indicate which plays are working well or poorly, or that a team's offensive or defensive coordinators need to reconsider their strategies.