If you score three in a game it's not that likely anyone is going to catch you at any level. You can't sustain that though. No-one scores 138 goals in a season.
If you neglect defending then you won't get very far, whichever division you're playing in. It's much easier to set yourself up to win games 1-0 regularly than 3-2. There's far less that can go wrong. I don't have any time for managers who play in a hopelessly naive style (hello Brendan), I'm not about to shrug my shoulders and say "we gave it a go" if we're leaking goals all over the place.
Given that our back four is fine unless we get a lot of injuries all in the same area all at the same time, and we have two of the best forwards outside the Premier League, our biggest issue at the moment is midfield, especially if we want to play both Afobe and Dicko. We don't have anyone to play on the left, Jacobs is currently the only option without putting someone wildly out of position and he isn't really in favour and isn't really a winger. We don't really have the central players to play in a two, if McDonald is a more or less guaranteed pick then we have a choice between Edwards (too easy to just walk through us), Evans (no mobility) and Price (no attacking threat at all to go with McDonald's zero goal threat), so it's never properly balanced. Wallace doesn't strike me as an answer in a two, but he's obviously been bought with a purpose in mind. As mentioned earlier in the thread I can see us moving to 4-3-3, we'll need at least two more forward/wing options and at least one other central midfielder if we do that.