Btw, Barcelona is the only team from the 1st division that's playing at home in the Round of 16 of the Copa del Rey...A bit odd, isn't it? I mean, the worst Barcelona we've seen this season has been in away games which they somehow managed to avoid in the next league cup game 
Barca isn't only. Real Sociedad will play against Osasuna at home. While all other teams will face clubs from lover divisions and there is rule that lover division team must play at home. If two same division teams will face, then draw will be made to decide who will play at home.And yeah, it's just Leganes, but now I'm more confident than if it would be played away
.For teams like Barcelona playing at home should not be a concern.
They need and can win the away games as well without a lot of strive. Playing at home is a great boost but they don't need the fans boost, they have stronger players that can play competitive in away games as well.