New proofs in combinatorics are usually interesting not only for the result, but for the technique.

For example, a proof using a sign-reversing involution, a proof using a bijection, a proof using RSK and a proof using crystal graphs all mean something for proving Schur positivity. However, a crystal proof usually implies the existence of an RSK proof and a bijective proof.

There are several open problems in my area that are of the form "find a proof using technique Y of statement X". Thus, when giving a proof of something, the main idea and technique used should perhaps even be in the abstract.