When the Boston Celtics stormed back to beat the Miami Heat in the last game of the regular season last Wednesday, it appeared to have sealed a top-four seed and home-court advantage in the first round.

Instead, Boston found themselves in a four-way tie with the Heat, the Atlanta Hawks, and the Charlotte Hornets. The C’s were given the fifth seed in the East.

After further review, it appears that an oversight of the tiebreaker rules cost the Celtics the fourth side.

Before the season began, the NBA revised its playoff format by lessening the importance of winning a division, giving the teams with the best records in the conference overall the top seeds. Rather than a division win, the first tiebreak criteria became head-to-head records.

The oversight? Darren Hartwell of NESN points out that the rule was only changed for two-team tiebreaks, meaning that the old division winner tiebreaker still applied for the four-time mess in the middle of the Eastern Conference playoff picture.

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So, despite the Miami Heat having a 0-3 record against the Celtics on the season, they were given the 3rd seed thanks to a division title, earned by having a better cumulative head-to-head record against the Hornets and Hawks.

From there, the remaining three teams were ordered by their respective win-loss records against each other, with the Hawks at 6-2, Boston at 3-4, and Charlotte at 2-5.

If the Heat were included in the four-way tie instead of a separate division winner selection, the head-to-head records would look like this: 6-4 for Boston, 7-5 for Atlanta, 5-6 for Miami, and 4-7 for Charlotte. The C’s would’ve had the 3-seed. The rule the league tried to take out ended up playing a huge role here.

Instead, they’re in for a tough series against the Atlanta Hawks. It will be exciting to see how this matchup pans out over the next couple of weeks.