Ask any Boston Celtics fan and they'll tell you that Marcus Smart is the heart and soul of the team. He won't be an All-Star and won't put up eye-popping stats, but Smart's value to the Celtics is irreplaceable.

In his sixth season with the team, Smart is the longest-tenured Celtic on the roster. The former No. 6 overall pick has never been a star and has averaged under 10 points a game on an unimpressive 37.4 percent field goal shooting for his career.

However, what the stat sheets won't always tell you is how much toughness, heart and hustle the former Oklahoma State guard plays with. Through 16 games, the Celtics are 12-4 and are playing better than most expected. Boston currently has the fourth-best defensive rating in the NBA (102.7) and is only 0.1 points from two teams ahead of them, per NBA.com. When Smart is on the court, that defensive rating is 100.7.

The Defensive Player of the Year award is usually given to the best defensive player on one of the best defensive teams, so Smart obviously fits the bill there. Smart is only nabbing 1.6 steals per game, but while that doesn't pop off the page, there are a lot of other factors that go into being an impact defender.

Smart is almost always matched up against the opposing team's best player and often takes on players at all five positions. The guard has already slowed down some of the NBA's biggest stars this season, including Giannis Antetokounmpo, Luka Doncic and Kawhi Leonard. Former Celtics Isaiah Thomas and Kendrick Perkins have both endorsed Smart as their early choice for DPOY, and if you've watched any Celtics games recently, you'd know why.

An incredible hustle play at the end of the recent Clippers vs. Celtics game perfectly encapsulated Smart's hustle and grit, while his clutch steal and dagger two games later showed off Smart's elite defensive instincts.

These winning plays are a big reason why he's so embraced by fans and vital to the Celtics' success. He has a knack for the ball and isn't afraid of a mismatch, bringing an unbelievable sense of energy and grit that any team would love to have.

For a player who made the All-Defensive First Team in 2018, Smart should receive more hype as one of the best defensive players in the league. He's not nearly as big of a name as someone like Kawhi Leonard or Rudy Gobert, but he's the reason the Celtics have one of the best defenses in the league.

If this keeps up, Marcus Smart should undoubtedly get more credit and be in the Defensive Player of the Year conversation at the end of the season.