The Boston Celtics lost a very winnable Game 4 on Sunday afternoon, headlined by rookie head coach Joe Mazzulla opting not to call a timeout in the dying seconds of both the fourth quarter and overtime to draw up a play.

Mazzulla caught a ton of heat for not stopping the game on two separate last-second offensive possessions; one resulted in a bricked three by Marcus Smart, the other a made triple that was released after the clock expired.

Both times, the rookie coach opted against taking a timeout, and admitted afterwards that not drawing up a play was a mistake.

“Hindsight is 20/20, I should have called [a timeout at the end of OT] to help us get a 2-for-1 or get a couple more possessions,” Mazzulla said on Monday, according to NBC Sports Boston.

“Obviously, 14 seconds left, down 1, you want as many chances as you can. So, definitely learn from that. If it doesn't go well, it's a mistake. I think the two lessons that you learn from that are, call it right away and get…two shots, get a couple extra possessions, or we gotta have a clear understanding as a team that we gotta go faster to get a shot.”

The overall sentiment around the basketball world was that opportunities were wasted, and that the Celtics would have won if the clock was utilized better by Joe Mazzulla.

“The strategy is advantageous if the offense can catch the defense flat footed, but on Sunday afternoon, Boston wasted valuable seconds advancing the ball up the floor before initiating their offense in the final 4.5 seconds,” wrote Deadspin's DJ Dunson on Monday.

“Having your five-man lineup fly by the seat of their pants is liable to turn into an emergency landing. A quick breather would have been a perfect time to iron out the process and dial up a go-to after-timeout play.”

Instead, the Philadelphia 76ers won the game and will now travel to Boston with the series tied at two games apiece. Game 5 is set for Tuesday night at TD Garden.