Perseverance of the whole in spite of the loss of individual elements

The phrase defense in depth (1,2) is somewhat related to the concept outlined in the question. As noted in wikipedia,

Defense in Depth ... is an information assurance concept in which multiple layers of security controls (defense) are placed throughout an information technology system. Its intent is to provide redundancy in the event a security control fails or a vulnerability is exploited that can cover aspects of personnel, procedural, technical and physical for the duration of the system's life cycle. [1]

Defence in depth (also known as deep or elastic defence) is a military strategy that seeks to delay rather than prevent the advance of an attacker, buying time and causing additional casualties by yielding space. Rather than defeating an attacker with a single, strong defensive line, defence in depth relies on the tendency of an attack to lose momentum over a period of time or as it covers a larger area. ... The idea of defence in depth is now widely used to describe multi-layered or redundant protections for non-military situations, both tactical and strategic. [2]

Note that terms redundancy and multi-layered, used in the above descriptions, can be used as adjectives suggesting the concept outlined in the question. Terms deep defense and elastic defense also are relevant.

The strategy described works because the player has set up multiple defenses at the same time. Therefore, I'd fill in your sentences with:

Player A's layered defenses won him the game.
If it wasn't for the commanding officer's layers of defense, the mission would have gone FUBAR.