Despite having the best record in the Western Conference, the Suns decided to trade Shawn Marion and Marcus Banks to the Heat for Shaquille O'Neil. The truth is there isn't much to say about this trade that hasn't already been stated elsewhere (here and here), but I'm going to do it anyway.
This deals makes no sense from a number of standpoints:
1) Player Value - Marion is simply the better player at this point of Shaq's career. Every single basic and advanced metric bears that out. Per game Marion averages more points, rebounds, assists and steals. He averages slightly less blocks, but far less turnovers. He also shoots better from the line and 3-pointers. Shaq's only real advantage is FG%.
Advanced stats like Wins Produced and Wins Produced Per 48 minutes put Marion way ahead. Marion's WP of 9.6 is 7th in the League at the halfway point of the season, only slightly behind possible MVP Lebron James. His WP48 (0.314) is ahead of stars like Kobe, Carlos Boozer, Yao Ming, and his former teammate, Amare Stoudemire. Shaq, however, has a WP48 of 0.102 and a WP of 1.9, which puts him at 132 in the league behind luminaries such as Daniel Gibson and Keith Bogans.
Even John Hollinger's PER ranks Marion ahead of Shaq just based on per-game production. Marion is 30th in the league at 20.25, while Shaq is 49th with a PER of 18.16. And PER doesn't even take into account defense, where Marion clearly trumps Shaq.
2) Health - Marion has played in 79 games or more every single year since his 2nd season. How about Shaq? Shaq hasn't played in that many games in a season since Marion's rookie year. He played 73 game in his first year in Miami, but since then Shaq has only played in about 2/3rds of his team's games. So even if Shaq was more productive on a per game basis, he just doesn't play enough games to justify this trade.
3) Finances - Shaq has two more seasons at 20 million per year after this season. Marion has a player option for 17 million dollars that kicks in at the end of the year. So instead of one more year at 17 million at most, they now have two more years at 20 million. Even though the Suns rid themselves of Marcus Banks' 4 million plus per year contract (which runs for 3 more seasons), they still come out way behind.
4) Style of Play - The Suns are a run and gun team. Shaq can barely make it down the court. Marion was their big-time defender, a guy who could take anyone from Chris Paul to Carlos Boozer. Shaq averages 4 fouls in less than 30 minutes per game. Marion can score in a variety of ways. Shaq can still post up, but he does not demand the same double team he did in the past.
The only argument for getting Shaq is that he is a center and the West (and especially the Suns' biggest nemesis, the Spurs) are full of big men. While that is true, there is no way Shaq can defend Duncan anymore, and I don't think he could even do much to stop someone like Yao. So what's the point?
Maybe the Suns didn't want to lose Marion for nothing in case he decided to walk. If that's true, why not wait a little longer and see if they could swing a better deal? And even if they couldn't, Marion will want to be paid a lot at the end of the year, and that is most likely to happen in a sign-and-trade. So they didn't have much to worry about.
When it comes down to it, Shaq is still a decent player, probably one of the top 10 centers in the NBA. When healthy, he is in the top 5. But Shawn Marion is a top player in this league, younger, more durable, fits the team's style better, and is cheaper. Why give him up for an aging Shaq? I just don't get it.