Every year is different. What happened last year, or the year before, or the year before, etc. means little. Everybody starts with the same record.
As for the Suns and key injuries... It is sad but true. Not simply the last two years, but in early 90's as well. It's a fact of life and with the differences between the top teams being so small, even small injuries can be enough to change the balance.
Two years ago the Spurs were better than the Suns, but losing JJ made it much harder for the Suns to have even a chance. The final outcome would not likely have been changed, but it was disappointing that the Suns couldn't really compete (although Amare did have a great series).
Last year the Suns were without Amare and KT plus Bell was banged up to the point of not being a factor. Would the Suns have won if healthy? Who knows, but certainly their chances would have been a lot better.
This year we get a lot of Mavs fans that insist that the Mavs are vastly superior to the Suns based on a couple of squeeker victories and the Suns losing streak when Nash was out.
Maybe the Mavs are the better team. If both teams are healthy in the playoffs, then we'll know for sure. But if the Mavs get all beat up and lose in the first round, it won't mean they are a bad team. Just unhealthy.