We can debate the level of dim star power or box office draw and of the four of these above-the-title performers has all we want... but there is no debating the size and importance of the roles they play. I'm willing to bet that not a SINGLE production of Funny Girl has EVER put the actor playing Eddie above the title.
They certainly didn't originally, and they certainly didn't when they did this production in the West End. But now for some reason they have.