I also think David Blatt is being slept on by a lot of NBA fans, particularly the ones that don't pay a lot of attention to international basketball.
On Blatt, I think there is a thin line separating an excellent coach (which he is) and a successful NBA coach (which he is not). I would have said the exact same thing if Spoelstra went to coach Maccabi Tel Aviv. Different rules, very different schedules and priorities, and most important different roles for the coach over all.
Until he proves in practice he can coach this team well (which would be a major challenge for
any NBA coach) I think people are right to point out the Cavs have a question mark sitting on their bench.
On a different note, I entirely agree with what you say about the defense, this is why many people who think Love> Bosh are wrong, let alone the lack of depth, chemistry etc. I do not see them winning a championship this year, unless they add a few more more pieces to their team
and get really lucky.