“What does it mean that Saul is also among the prophets?”
The phrase in question comes up a couple of times in scripture, in 1 Samuel 10 and 19. The writer of 1 Samuel tells us that the (rhetorical) question “Is Saul also among the prophets?” became a proverb in Israel. It definitely meant something to the people of God, though not necessarily anything particularly complimentary to Saul.
Can you imagine becoming the subject of a proverb? It might not be as much fun as we think.