[yorwba]

From the "related work" section of the paper:

The nowadays surprisingly poor performance of the models in Hill et al. (2016) can at least partly be explained because 1) they use poorer (older) word embeddings; and 2) FastSent sentence representations are of the same dimensionality as the input word embeddings, while they are compared in the same table to much higher-dimensional representations.

See also figure 1 for the increase in performance across tasks when the embedding dimension is increased.