Watching the Celtics-Lakers game last night, the topic of instant replay came up. Some background: NBA referees can use instant replay in certain situations, as detailed here:
Replay wasn't available for a crucial play last night. With 1:05 left to play and the Celtics up 87-82, Ray Allen shot what appeared to be an air ball as the shot clock was about to expire. After Celtics' center Kendrick Perkins grabbed the rebound, the whistle was blown and it looked like the Lakers -- who seemed to have the momentum at that point -- would get the ball back.
The NBA instituted instant replay before the start of the 2002-03 season, originally to review period-ending baskets and fouls, and a number of triggers have since been added.
Replay is used for officials to confirm a flagrant foul warranted an ejection, or that players left the bench during an altercation. Referees can now go to the monitor to see if shots or fouls came beyond the 3-point arc, whether they beat the shot clock, or if there was a clock malfunction.
The system was expanded this season to out of bounds possessions in the 2 minutes of regulation or overtime.
Instead, the refs huddled together and determined, without instant replay but with plenty of advocacy from the Celtics and Lakers' respective benches and perhaps the Boston crowd, that the ball actually glanced the rim. The Celtics got the ball back with a fresh 24 seconds on the shot clock and would go on to win the game.
While it's not clear what would have happened had the Lakers gotten the ball back, there seems to be a real possibility that they would have won the game. Kobe was completely dominant in the second half, despite pretty tight defense by Tony Allen, Ray Allen, Paul Pierce, and anyone else the Celtics tried in vain to stop him. From the Lakers' perspective, going back to LA with a 3-2 advantage in the series would seem completely different from going back down 2-3. The call on whether the ball hit the rim, in other words, may have changed the outcome of the series.
One of the difficulties of adopting instant replay is figuring out when it should be used and when it shouldn't, and how to justify the lines of demarcation. If instant replay is allowable for determining whether someone got a shot off before the 24 second clock expired -- which it is under NBA rules -- why isn't it okay to use it to see if a ball hit the rim?