They had a stellar month of March, only dropping three games, which enabled them to climb all the way up the standings and regain the fifth seed in the Eastern Conference.
In addition, Miami has won six straight road games, which is their longest streak in three years. They sit nine games over the .500 mark at 43-34, which is also their best record since 2007.
The Heat are playing their best ball of the season at the right time with only five games remaining and the team in the thick of the playoff race, holding a slim half game lead over the Bucks and a 2.5 game lead over the seventh-seeded Bobcats.
Miami's recent surge is a product of their fierce defense that ranks best in the league in most categories.
Second-year head coach Erik Spolestra has instilled a strong sense of defensive prowess in his team, which has been passed down to him from former Heat skipper Pat Riley and his defensive minded approach.
The Heat have finally realized that their defense is what fuels their game and makes them successful. They have learned that their defense gives them a chance to win every night and it has been their formula for success in their recent winning streak.
Miami is now second in the NBA in points allowed, limiting opponents to an impressive 94 points per game. They only trail their division-mate Charlotte Bobcats by 0.5 points, who allow 93.5 points per game, for the least amount of points allowed.
They rank No. 1 in the league in lowest field goal percentage against at 43.7 percent per game and they are tied for third-best in three-point percentage allowed at 33.9 percent.
In addition, they are tied for second in the NBA for blocked shots, swatting 5.7 shots per contest.
Miami takes a lot of pride in its defense and relies heavily on it in late game situations. They have the ability to play lock-down defense every night that is among the most ferocious defenses in the NBA.
Their defensive effort has made them a playoff team this season and the Heat are among the best defensive squads in the NBA.
The Heat are equipped with defensive weapons both in the starting lineup and off the bench.
Jermaine O'Neal and Dwyane Wade highlight the defense for the starting lineup. O'Neal is still an excellent inside defensive presence and shot blocker, averaging 1.4 blocks per game. He still has the ability to change shots and hassle the best big men in the league.
Wade is undoubtedly one of the top defensive players in the league.
The All-Star averages 1.9 steals per game, which is third-best in the NBA and leads the Heat, and he is good for 1.1 blocks per game. He is hands-down the best shot blocking guard in the league and is an overall relentless defender.
Quentin Richardson is also a solid defender in the starting rotation. He is fourth on the team in steals and he can be counted on to take charges on a nightly basis.
The Heat's second unit also contains some great defensive weapons.
Point guard Mario Chalmers, who hasn't been as effective as last year, is still a reliable defender. He averages 1.2 steals per game, which is second on the team. He receives a lot fewer minutes this season in a reserve role, but still contributes highly on defense.
Miami's defensive frontcourt off the bench is even more impressive, with Dorell Wright, Udonis Haslem, and Joel Anthony making up that cast.
Wright's length and athleticism allows him to be a dangerous defender.
At the small forward position, he receives defensive assignments against the NBA's elite players and does a solid job. Wright has finally started to come together on the court and is finally part of the regular rotation.
Haslem leads the Heat's second unit and brings lots of energy off the bench with his hustle and motivation. He is a hounding defender that is able to out-rebound bigger opponents. Haslem also has a knack for sacrificing his body to take charges, further adding to his value to the Heat's roster.
Anthony has been a nice surprise for Miami. He might be the most unknown player in the league, but has quietly been one of the team's most valuable players in their recent surge.
Anthony has started in place of the injured Jermaine O'Neal for the last four games and responded well. He has averaged six points and 4.2 rebounds in those four victories and the Heat are 11-3 this season with Anthony as their starting center. He has 100 blocks on the season, which is the most on the team.
When both the bench and the starters are on defensively, the Heat are one of the most lethal defensive teams in the NBA.
In their current eight-game win streak, their defense has limited opponents' scoring to 82.9 points per game.
Miami hasn't allowed 100 points or more in more than two weeks.
While an argument could be made that during the streak, the Heat have only faced three playoff-contending teams (Milwaukee, Toronto, and Charlotte), it's undeniable that the Heat have noticeably picked up their defense.
Miami is playing with a sense of urgency as they know they have no room for error with the Bucks scratching at their heels for the fifth seed. Miami has worked hard to recapture the fifth spot and they don't want to relinquish it.
To accomplish that, the Heat will simply have to maintain their defensive intensity. They have relied on it consistently over the past month to win ballgames and rise up the standings.
If the Heat continue that defensive mentality, they will be a very dangerous team in the postseason. With five games left to determine their playoff fate, Miami will turn to their defense to help them prevail.
If Miami can carry that defensive momentum into the playoffs, they have the opportunity to be a surprise threat.