I am not a mechanic and I have never developed much of a knowledge base on the workings of car engines, but I do have a basic understanding of spark plugs (among other parts of cars): they make combustion happen. The spark plug delivers the electricity that sparks the fuel and makes the combustion, which kick-starts the engine’s operation, happen.
While I will not spend too much time completing the analogy for the rest of the squad (who represents the crank-shaft, or the pistons, etc.), I think even casual basketball fans can relate to the idea that every team needs a spark.