Both seem off to me, but are consistent with the rest of their rankings (GS for example had a best case of 67 and worst of 52; Houston and Toronto were both 61 and 45).
For most teams I would think even the worst case was generous, but the C's had pretty much a worst case last season and still won 55 games. You're telling me there's something worse than that? I think Boston should have had GS's numbers (while GS best case should be 70+), Houston's best case is 61 while they actually won 65 games last year (and ESPN actually mentions this in their first line about Houston but does nothing to answer it, seems lazy to me).