Unless you have your shaman on tank healing (only) he should really utilize his aoe abilities more often. On most fights you posted CH, HR, and SLT are barely used (if at all). If he incorporates those into his rotation more so he should be within ~5-7%.
RDruids do seem to really rule the meters on 10mans, but if your shaman uses his abilities to the best shaman healing characteristics he'll catch right up.