OK now lets look at this position.
White will always win this type of position irrespective of where the B might be but the black K must not cross the KB file as it will then be able to head towards the safe corner where mate cannot be forced.
So 1. ... Bg1;
A double attack by the Rook threatening mate and the B must be avoided
and this is the only square to do that eg if 1. ... B b2; 2. Rb7 .. Be5; 3. Re7 wins
2. Rf1 .. Bh2;
3. Rf2 .. Bg3;
4. Rg2 .. Bd6;
5. Rd2 .. Be7;
6. Ra2 winning.
Whilst a few other winning positions exist these are exceptions and unless the stronger side is able to exchange off into the favorable sort of position given in these example the game is likely to be drawn.