Considering the systems tuned on BLEU, we observe that the 5-gram NNLM and RDLM are best in terms of BLEU and TER, but that RDLM is the only winner 9 according to HWCM f and METEOR.
we observe a sizable gap of 0.6 HWCM f points between the NNLM and the RDLM systems, despite similar BLEU scores.