I think the reason for this is that Dish doesn't currently carry NESN HD.
I have heard that Dish "doesn't carry" some RSN's HD, including NESN. I am confused as to why. That would mean that sports fans in Boston (and other areas) would have to subscribe to some other service, other than Dish, in order to see their sports teams in HD. This hardly seems the way to keep or increase their subscriber base, especially since they already have the RSN. It can't be that big deal to also get RSN HD rights...
Further to my previous post -- I continue to rant. Today's CI schedule has 6 games and none are scheduled for HD broadcast on CI. That makes 2 games out of 15 over the past 2 days that have been in HD, and Dish claimed "a majority" of the games on CI would be in HD. It actually looks like that was their intention as there is a separate HD channel set up for every SD channel on CI -- they just haven't followed through on providing the HD telecasts...