Here's the thing. Nash isn't just a really good PG. Anyone who think he's just really good is missing the facts. A Nash led team has led the League in offense for the past five seasons. That's not a coincidense, considering the amount of player turnover both Dallas and Phoenix has had.
If Dirk went down and Terry averaged 20-10, he wouldn't be enough to get them to the Conference Finals. I'm not sure Dallas would make the playoffs without Dirk, so your argument is very flawed.
Fact is, Last year many people questioned Nash by saying "but he has Amare". Well, this year he didn't and they have gone farther this year without him than they did last year with him. This is because of Nash.
He may not be a top-10 player in reguards to pure skill or potential, but on impact of a team, he's easily a top-3 player. He makes everyone better. Don't give me the "Phoenix" system either, but if you knew anything about the Suns, you'd know the system is Steve Nash. D'Antoni has said on many occasions he just lets Nash run the show. Everything you see is Nash. Is is the writer and director of the Suns offense. Everything is based on his play, which is why when Nash struggles, the Suns struggle and why when Nash plays good, the Suns play good. He's the end all, be all of this team. No one player in the League has more responsibility within an offense and no one player in the League can get so much out of so little.
And Yes, I do mean little.
Diaw... say what you want,, but he was a scrub throw in as part of the JJ trade. Phoenix ups have admitted to being surprised at his skills.
Jones... when he got consistant playing time (lost it around March due to injuries and Tim Thomas' acquisition) he was a 14-point, high percentage shooter in his first real year of playing time.
Barbosa... Look at last year's numbers (as a backup to Nash), then look at this year's numbers (as a SG next to Nash).
Tim Thomas... He was traded three times within the last three years and was eventually waived. He's been a career underacheiver and yet is now the best offensive frontcourt player the Suns have.
Bell... solid numbers in Utah have been turned into a JJ'esque average of 16 points, 4 rebounds and 3 assists with very high percentages that were never there before Nash.
The MVP took a hodgepodge of scrubs, castaways and role players and has them in the Western Conference Finals without the team's starting frontcourt.
True everyone above had talent, but it took Nash to maximize it.