American football Two-point conversion

In American and Canadian football, a two-point conversion or two-point convert is a play a team attempts instead of kicking a one-point conversion immediately after it scores a touchdown. In a two-point conversion attempt, the team that just scored must run a play from close to the opponent's goal line (5-yard line in amateur Canadian, 3-yard line in professional Canadian, 3-yard line in amateur American, 2-yard line in professional American) and advance the ball across the goal line in the same manner as if they were scoring a touchdown. If the team succeeds, it earns two additional points on top of the six points for the touchdown. If the team fails, no additional points are scored. In either case, the team proceeds to a kickoff.

Various sources estimate the success rate of a two-point conversion to be between 40% and 55%, significantly lower than that of the extra point, though if the higher value is to be believed, a higher expected value is achieved through the two-point conversion than the extra point.

Adoption of rule

The two-point conversion rule has been used in college football since 1958, and more recently in Canadian amateur football and the Canadian Football League (1975). In overtime situations in college football, the two-point conversion is the mandatory method of scoring after a touchdown beginning with the third overtime.

The American Football League (AFL) used the two-point conversion during its ten seasons from 1960 to 1969. After the NFL merged with the AFL, the rule did not immediately carry over to the merged league, though they experimented in 1968 with a compromise rule (see below). The NFL adopted the two-point conversion rule in 1994. Tom Tupa scored the first two-point conversion in NFL history, running in a faked extra point attempt for the Cleveland Browns in a game against the Cincinnati Bengals in the first week of the 1994 season. He scored a total of three such conversions that season, earning him the nickname "Two Point Tupa".

The NFL's developmental league, NFL Europe (and its former entity, the World League of American Football), adopted the two-point conversion rule for its entire existence from 1991 through 2007.

Six-man football reverses the extra point and the two-point conversion: because there is no offensive line in that game variant, making kick protection more difficult, plays from scrimmage are worth one point but successful kicks are worth two. It is also reversed in many high school football and youth football leagues, since there are not often skilled kickers at that level. A variant of this, especially at the youth level, is to allow one point for a running conversion, two points for a passing conversion, and two points for a successful kick.

The Arena Football League has recognized the two-point conversion for its entire existence (in both its original 1987–2008 incarnation and its ongoing revival), allowing for either a play from scrimmage or a drop kick to be worth two points. (The additional extra point for a drop kick is unique to arena football.)

In 1968, leading up to the AFL-NFL merger, the leagues developed a radical "compromise" rule that would reconcile the fact that the NFL did not recognize the two-point conversion but the AFL did: the relatively easy extra point kick would be eliminated and only a play from scrimmage would score one point. The rule would be used for the interleague matchups for that preseason, and would not be tried again. Both the World Football League and the XFL revived this concept, making it a point not to institute a two-point conversion rule so as to eliminate the easy kick. What would constitute a two-point conversion in other leagues only counted one point in the AFL-NFL games, WFL, or XFL. The WFL called it the "Action Point," used after touchdowns which the WFL counted as seven points. However, the XFL later added a rule in the playoffs that allowed the scoring team to score two (or even three) points by successfully executing a play from a point farther from the opponent's end zone (two points if the team could score from the five-yard line and three points if they could score from the ten-yard line).

During the summer of 2014, the conversion by place kick was under review by the NFL. This new format would award seven points for a touchdown without an extra point attempt, eight points with a successful conversion by running or passing, and six points with an unsuccessful extra point attempt. This new format was proposed because of the almost certain probability of making a conversion by place kick (1,260 out of 1,265 for the 2013 season). This proposal was never considered at the league owners' meeting in spring 2014; instead, the league used the first two weeks of its preseason for an experiment that moved extra point attempts back to the 20-yard line with the condition that if a team opted to attempt a two-point conversion instead, the line of scrimmage on the try would remain at the 2-yard line. The league adopted a slightly modified version of this rule starting with the 2015 season, with the line of scrimmage for extra-point kick attempts at the 15-yard line instead of the 20.

Defensive two-point conversion

In American college, professional, and Canadian football (as well as, for a significant period of time, the Arena Football League, where missed extra points are rebounded back into the field of play), a two-point conversion attempt or a blocked PAT attempt where the defense gains possession of the ball can be returned by the defense to the other end zone to give the defensive team two points. The team that scored the touchdown then kicks off as normal. This is rare because of the infrequent use of the two-point conversion and the rarity of blocked extra points, combined with the difficulty of returning the ball the full length of the field. It has proven the winning margin in some games. Only once has an individual player scored two defensive two-point conversions in a game: Tony Holmes of the Texas Longhorns in a 1998 game against the Iowa State Cyclones.

On May 19, 2015, the NFL owners adopted a proposal to permit a defensive two-point conversion for the 2015 season. On December 6, 2015, Stephone Anthony of the New Orleans Saints became the first NFL player to score a defensive two-point conversion, when he returned a blocked extra point kick from Graham Gano of the Carolina Panthers.

College football has allowed for defensive two-point conversions since 1988.

High schools that follow the rules of the National Federation of State High School Associations (all U.S. high schools except those in Texas and Massachusetts, which use NCAA rules instead) do not allow defensive runbacks of recovered conversion attempts, and any recovery of the ball by the defense during the try is immediately blown dead and ruled merely as 'no good'.

Conversion safety

NCAA and NFL rules dictate that when a safety occurs during a two-point conversion or point-after kick (officially known in the rulebooks as a try), it is worth one point. It can be scored by the offense in college ball and the NFL (following an NFL rule change in 2015) if the defense obtains possession of a live ball in the field of play, propels the ball (by carrying it or fumbling it) into its own end zone, and then is downed there with the defense in possession of the ball. This event has only occurred twice in NCAA Division I history. Before 2015, the only scenario in which a one-point safety could have been scored in the NFL would have involved the defense kicking or batting a loose ball out the back of the end zone without taking possession of it.

In college or pro ball, a conversion safety could be earned by the defense if the offense retreated with the ball all the way back into its own end zone. A more plausible scenario would involve a turnover on the extra point attempt followed by a lost fumble before the defensive player reaches the end zone, with the ball finally being downed by the offense in its own end zone. Although such a conversion safety has never been scored by the defense, this rule provides the only way in which a team could finish the game with only a single point (with the exception that Canadian football allows another one-point play called the single or rouge).

Mathematical analysis of the two-point conversion

In 2007, blogger Eric Menhart analyzed the value of going for a two-point conversion compared to trying an extra-point kick in the National Football League, concluding that teams are better served kicking the extra point in most cases. This was consistent with the results in the XFL, which had an average success rate of 40% for their one-point conversions (the XFL required scrimmage plays for one point and did not allow a kick-for-try). This counters Tuesday Morning Quarterback columnist Gregg Easterbrook's theory that, because on average five yards are gained on a typical scrimmage play, the two-point conversion would result in a greater average point return per conversion attempt. Furthermore, Easterbrook cites the Football Prospectus, which states that the average success rate on a two-point conversion is between 50% and 55%, depending on the historic time frame analyzed and the situations in which the conversion is attempted. Such situations usually involve goal-line defenses and are thus not typical scrimmage plays, resulting in shorter average gains. Regardless of the actual success rate, professional teams, preferring the near-certain single point, seldom attempt the two-point conversion, barring circumstances where converting for two points will “balance the score” or allow the team to tie or win the game.

There is a relatively common game situation in which the two-point conversion can be an optimal strategy even if its likelihood is somewhat under 50%. In this situation, a team down fourteen points in the final minutes must score two touchdowns while keeping its opponent scoreless in order to tie or win the game. The team could choose to go for two after the first score, because if successful, the team could then kick an extra point following the next score to secure a win. On the other hand, if the two-point conversion fails, the team still has a chance to succeed on the next two-point conversion to get to fourteen. As long as the probability of converting any individual two-point attempt is higher than 38.2% percent, it is optimal to adopt this strategy. Notably, Texas Longhorns coach Darrell Royal successfully used this strategy to defeat Arkansas in 1969's Game of the Century.

The minimum probability of converting a two-point try either on the first attempt (securing a win) or the second (securing a tie in regulation time) must be higher than the maximum probability of missing both (securing a loss). This cross-over point occurs at a value of 38.2%. At this value, the probability of missing both is .618 x .618, or 38.19%. (The probability of failure to convert is "1 minus the probability of converting the two-point try", (1-.382), or .618.)

Two-point conversion chart

This version of the two-point conversion chart was first developed by Dick Vermeil in the early 1970s when he was offensive coordinator under Tommy Prothro at UCLA. The chart is still used by coaches in determining whether to attempt a two-point or one-point conversion after a touchdown in various situations. The score margin listed in the chart is the margin after the touchdown is scored, but before the conversion is attempted. (The chart shows that when a team trails by eight points after scoring a touchdown, the situational strategy born of desperation (as described above) contradicts it.) A study has shown that the success rate in the NFL between 1994 and 2012 was 44.8%. In the Canadian Football League, the success rate has even been as high as 72%. With the 2015 NFL rule changes that require the offense to line up at the 15-yard line on an extra-point kick attempt and that allow the defense to possess the ball after a blocked kick or turnover and to score a defensive two-point conversion, this chart is subject to potential revision because of altered expectations of success.

Lead By		Trail By
1 Point	Go For 2	1 Point	Go For 1
2 Points	Go For 1	2 Points	Go For 2
3 Points	Go For 1	3 Points	Go For 1
4 Points	Go For 2	4 Points	Go For 1
5 Points	Go For 2	5 Points	Go For 2
6 Points	Go For 1	6 Points	Go For 1
7 Points	Go For 1	7 Points	Go For 1
8 Points	Go For 1	8 Points	Go For 1
9 Points	Go For 1	9 Points	Go For 2
10 Points	Go For 1	10 Points	Go For 2
11 Points	Go For 1	11 Points	Go For 1
12 Points	Go For 2	12 Points	Go For 2
13 Points	Go For 1	13 Points	Go For 1
14 Points	Go For 1	14 Points	Go For 1
15 Points	Go For 2	15 Points	Go For 1
16 Points	Go For 1	16 Points	Go For 2
17 Points	Go For 1	17 Points	Go For 1
18 Points	Go For 1	18 Points	Go For 1
19 Points	Go For 2	19 Points	Go For 2
20 Points	Go For 1	20 Points	Go For 1

SPORTS

American Football

Game play in American football consists of a series of downs, individual plays of short duration, outside of which the ball is dead or not in play. These can be plays from scrimmage – passes, runs, punts, or field goal attempts (from either a place kick or a drop kick) – or free kicks such as kickoffs and fair catch kicks. Substitutions can be made between downs, which allows for a great deal of specialization as coaches choose the players best suited for each particular situation. During a play, each team should have no more than 11 players on the field, and each of them has specific tasks assigned for that specific play.