It doesn't. However, one of two things is true if you are "better" than the division you play and still losing more than winning. First, you may be giving your team directions but not winning them over first, so your team gets frustrated with the criticism and plays worse and makes more mistakes than they do in other games they play. If this happens then you have worse than average teams unless someone is doing the same thing on the other team. That would mean you have to carry harder to make up for the influence you have on your team, rather than just being better than average. Second, it is possible that you are average skill level in lane, so your lane is going even but not winning, and that isn't enough to carry no matter what role you play. Bronze is a reckless division and people underestimate stuff a lot. If you get good with a high damage support like brand, Annie, Morgana, or Lux, you can do more damage than carries as a support in bronze. People don't expect good supports in bronze so first blood and often a double is pretty doable consistently.