Great, capable individuals can definitively make a difference. I know a lot of them; sharp, hardworking people that could easily impress you with their knowledge after a 5-minute conversation with them.
Sadly, you need something else to build a team. It's not enough to be great at what you do; you also need to be good at working with others. I've seen time and time again talented developers that have no clue about being part of something bigger than themselves.
Just like a baseball team, it's not about packing as many stars as possible under the same roof, but about finding the right balance and chemistry that will lead to winning games.
With every new interview, I've found myself asking more questions to uncover that side of the candidates. I don't stop anymore as soon as I realize how great developer you are, but I try to dig deeper to make sure you'll be a good fit for the rest of the orchestra.
The secret is right at the intersection of a great developer and a great team player.