The rest of the feed is cable exclusive to Cox Cable. D* is only able to get the feed for MLBEI due to the part ownership of the package along with MLB and Indemand, which Cox is a part of.
Plus, SD4 is not viewable even with EI in the hometown area. As an RSN, it would be viewable in the hometown area and, therefore, not exclusive to Cox.
As for MLB.tv and satellite radio, MLB got the jump on the local guys by making all internet and national radio rights centrally owned. They were not able to do so in time for satellite TV (which they learned from). That is why the newer technologies have full coverage.