Lee spiked the ball with 18 seconds left

And the clock started at 18 seconds.

SO it can be seen empirically that if you have 1 second left on the clock, you have time to spike it.

That being said, the whistle was blown at 17 seconds and the clock ran down to 15 for some reason. Really don't understand it.

3 seconds run off the clock on a spike. That could have made a huge difference in the game.

Clock operators