First, Brollan is a gamble, we don't know how good he is/can be, but we know GTR can be the best player in the world.
Second, it's not all about firepower, for example, yesterdays GTR play on train, it was 1 v 3 i think, where GTR kills someone from Ivy then goes ct resp kills there and back to Ivy, that's experience, Godlike game sense. Many upcomers would want to prove themselves and try outaim opponents.
GTR is a crucial part of new NIP, and that part is not star player, they don't even need more firepower. Give them some time and they will be a constant top team. Not saying top1, but everyteam can't be top1.