While everything seems to work out perfectly for the Suns, there's one other factor to consider -- restricted free agents Robin Lopez and Aaron Brooks. Phoenix submitted qualifying offers to each player, which means their cap holds are still on the team's books. $7,156,505 for Lopez and $5,041,730 for Brooks (note that those are the amounts of the players' cap holds, rather than the qualifying offers). Those figures would push Phoenix well over the cap threshold, which wouldn't be permitted if the team wanted to use its cap space on agreements with the aforementioned three outside free agents.
http://www.hoopsrumors.com/2012/07/the-suns-and-the-salary-cap.html#more
Much more detail at the link.