Benchwarmers are members of sports teams who rarely if ever play in actual games. Rather, they spend most of the game sitting on the sidelines; they're called benchwarmers because they are thought to contribute nothing other than the body heat that they pass onto the bench. In practice, this usually isn't true--most benchwarmers cheer on their teammates and play important roles in practice. Benchwarmers are sometimes called scrubs, but there's a subtle difference: scrubs clearly suck, while benchwarmers may be players who are good, but just not good enough.