A bullied kid has 1 dream: to become the next big thing in soccer. But what he doesn't know is that there will be sacrifices to make.

What sacrifices? That's the question I asked myself.

Fear of being bullied is the raw material for a sufficient character flaw and challenge to overcome to realize his dream but the description of the dream itself needs to be more concrete and specific than the next big thing.? What does that mean?

For example, as he is a "kid", his dream could be to make the team, lead it to a championship season.

For the purposes of a logline (and plot), the dream has to be more concrete and specific than "the next big thing." Like, he wants to make the school team. Play in the starting lineup. Lead the team to a championship season.

Being bullied is the raw material for a sufficient character flaw and challenge: he has to overcome his fear of being bullied, and overcome the bullying itself to show up for try outs, make the team, etc.