Bastille does have a good singer. Without their lead singer, Bastille would not be as good as they are. A good lead singer makes or breaks a group, and with Bastille focusing on more singing now then in the past, they are doing a lot better then they were before.
They're only as good as their lead singer, and as they've shifted more from being just a group that produces electronic music to a group that actually sings, their chart performance has gotten much better. That is because when they sing, the lead singer is really good at what he does.