Call it youthful exuberance, inexperience or whatever, you can tell which team is used to playing on the NBA’s biggest stage.

The Miami Heat have made all the right plays, while the Oklahoma City Thunder have struggled through several costly rookie mistakes. Just take a quick look back at the Heat’s 104-98 win over the Thunder in Game 4. Trailing 101-98 with 17 seconds left, the Thunder forced Dwyane Wade into a bad shot on the baseline as the shot clock neared zero. Udonis Haslem and James Harden battled for the rebound until a jump ball was called. By rule, the shot clock was reset at five seconds.

The Heat gained possession after the jump ball and Russell Westbrook immediately fouled Mario Chalmers, thinking the shot clock was reset to 24 seconds. It was a costly mistake, as Chalmers hit both free throws to give the Heat a 103-98 lead. That was just one example of how rookie mistakes have cost the Thunder. Miami leads the series 3-1. Game 5 is tonight (Thursday) at 9 p.m. in South Beach.

No one should be surprised at Oklahoma City’s penchant for committing mental errors late into the games. Their top three players–Westbrook, Kevin Durant, Harden–are all aged 23 or younger. Even Serge Ibaka is only 22. Meanwhile, this is third trip to the NBA Finals for LeBron James and Wade, while Haslem won a title with the Heat in 2006. The Thunder has Derek Fisher and Kendrick Perkins, who both have rings, but that’s about it.

Another aspect of the Heat’s win was the lack of punch from the Thunder’s support players. Westbrook (43 points) and Durant (28) combined for 71 points, while the rest of the squad scored 27 points on 35.5 percent shooting. Harden (8 points) has been invisible, while Ibaka hasn’t been much help either. Cutting down on the mistakes late and getting Harden going is the key for the Thunder.

If either of the two aforementioned problems are corrected, the Heat won’t have to leave Miami to play another basketball game until next October.