The slow speed data points (A) are using the old satellite links. The medium speed links (B) are asymmetric -- outbound via satellite and return through the cable. The high speed links (C) imply two way cable traffic.
A number of people commented on Madory's post, some indicating that they had indeed noticed faster speed in accessing Cuban servers, but, consistent with the Renesys data, others did not.
Madory updated the data in March. As we see here, the majority, though not 100 percent, of Telefonica traffic is being carried over the cable.
Regardless, if Cuba lacks the political will and domestic infrastructure to connect users to the cable, it will have little practical effect. The Cuban government has said the first applications of the cable would be those that benefit society. It seems to me that university and medical connectivity would fill that bill and be low-hanging fruit.
It has been three months since Madory first detected traffic. Has anyone noted any improvement in their service?