Agree with what Roy and Nick have been saying in Cleveland's defense. The stakes are higher and a KG-led team will respond. The man-to-man and help defense will be stellar all around, and Atlanta will find baskets incredibly hard to come by.
While I agree with Champ that our wings are likely our weak spot, it's certainly not due to a lack of defense at those spots. Wallace and Allen may not be the best scorers, but they're two guys who can defend Wade and Pierce as well as anyone. We will carefully balance the minutes in this series so that Wade and Pierce can never get too comfortable, but also so that we get enough offense from Crawford and Butler.
Some of our earlier matchups in these playoffs have also had incredibly tough front lines to put up against Horford and Garnett. In the first round, we saw Millsap/Asik/Amar'e, and in the second round we saw Lopez/ZBo/Sanders. Nene/Boozer, while still a good 4-5 combo, is easily the weakest of these three platoons. Horford and Garnett should be at their best on both ends of the floor, and that will be a difference maker here.
One last thing: I don't like to nitpick, but I don't think you can name Jameer Nelson as a premeire PG. He was once an all-star, yes, but that was when his efficiency was through the roof, shooting over .500 from the floor and .450 from three (and 88% from the FT line). Over the last few seasons, those numbers have steadily declined, and last season he shot below .400 from the floor. Ty Lawson is clearly the better PG in this matchup, and he's obviously better than Lin too.
It's a fight between "Old Man Strength" and the KG Way. I think KG's team will pull this one out fairly easily.