I don't know who is the best, but Monk is my favorite.
Another category... all time blaze of glory single great performance that came out of nowhere before fading back into obscurity...
For that, I think Timmy Smith is the answer

That's a pretty specific category. Not sure anyone can be beat Timmy on that one.
John Druce would be a candidate. He scored 14 goals in 15 playoff games one postseason. He made the SI cover, which said, "The Druce is Loose". He didn't totally drop off the map, though, following that postseason performance. He had a nice season the next year with 22 goals.