1. Permitting a winning combination
2. Black is paralysed
One side is said to have a lead in development when they have more pieces involved in the game. A lead in development, if not neutralised, may translate into either a quick win or a long-term positional advantage for its possessor.
In position 1 (Liiva - Skrebnevskis, 1993), while black is a piece up, he is effectively the a8 rook and c8 bishop down, as they are yet to influence the game. White must act immediately or black will get these pieces into the game. He wins by force by means of the combination 19. Rh8!! KxR 20. Bxf7! making mate via Rh1 unavoidable.
In position 2 (Kasparov - Petrosian, 1982), black's deficit in development is the same as seen in position 1, but its long term nature means white merely offers to exchange queens to exploit it.
See: 'Misplaced piece' and 'Initiative'.