The third of five children, Allen was born at Castle Air Force Base near Merced, California, the son of Walter Sr. and Flora Allen. A military child, he spent time growing up in Saxmundham in England, Altus in Oklahoma, Edwards Air Force Base in California, and Germany. After years of traveling and constant moving, he moved to Dalzell, South Carolina where he would attend high school for the next four years. When he first arrived, he was always the odd man out that kids often picked on for his formative language that he used due to his elementary years in Britain.

Allen rejected a two-year, $12 million offer to return to the Boston Celtics and accepted a three-year deal with the Miami Heat, who were limited to their mid-level exception amount of slightly more than $3 million per season. During Allen's first season with the Miami Heat, he averaged 10.9 points per game and made 88.6% of his free throws while playing an average of 25.8 minutes per game. On April 25, 2013, while playing Milwaukee in Game 3 of the first round of the playoffs, Allen made his 322nd career three-pointer in the playoffs, which broke Reggie Miller's record for most three-pointers made in NBA playoff history. Allen returned to his favorite #34 jersey upon joining the Heat.  In Game 6 of the NBA Finals against the San Antonio Spurs, as the Heat trailed by three points, Allen made a game-tying 3-pointer with 5.2 seconds left in the fourth quarter. Having rallied from a 10-point deficit at the end of the third quarter, the Heat won in overtime 103-100 over the San Antonio Spurs and forced a seventh game in the series. With the Heat leading 101-100, Allen stole the ball from Manu Ginobili under the Spurs' basket and drew a foul with 1.9 seconds remaining in the overtime period. Allen made both ensuing free throws to put Miami up 103-100. Allen played 41 minutes in Game 6 off the bench and scored 9 points on 3-for-8 field goal shooting; his game-tying three-pointer was the only three-pointer he made in three attempts. Allen also had one defensive rebound and two assists. In Game 7, which the Heat won 95-88 to win its second consecutive championship, Allen played 20 minutes off the bench. Although he made none of 4 field goal attempts and had 3 turnovers, Allen recorded 4 defensive rebounds and 4 assists.  On June 29, 2013, Allen picked up his $3.23 million player option to stay with the Heat through the 2013-14 NBA season. During the regular season, Allen played in 73 games, starting 9 of them, averaging 9.6 points and shooting 37 percent from three point range. In the playoffs, Allen scored 19 points on 4-7 three point shooting in game 4 of the conference semifinals against the Brooklyn Nets. Then in Game 3 against the Indiana Pacers in an Eastern Conference Finals rematch, Allen hit four 3-point shots in the fourth quarter and put them up 2-1 in the series. The Heat won the series in six games to advance to the NBA Finals for the fourth straight year and Allen's second. The Heat faced the Spurs again in the 2014 NBA Finals, but they lost the series in five games.

What was his overall stats?
During Allen's first season with the Miami Heat, he averaged 10.9 points per game and made 88.6% of his free throws