Why did the Suns trade for Shaq?

Sorry, I'm a little late to the party with my thoughts on the deal, but this has been about the busiest week of my life.

On the surface, this appears to be an almost senseless trade by the Phoenix Suns. They're one of the top contenders in the Western Conference, and yet they have traded away a guy that is an almost perfect fit in their system (Shawn Marion) for a guy that appears to be the exact opposite of the type of player that they'd look for (Shaq Fu). I think we can all agree the Suns seem to be a pretty smart franchise... which begs the question, why? Why make this deal?

For one, there have been a lot of rumors that Shawn Marion and Amare Stoudemire don't get along that well. Obviously I don't have any inside information on that, but if true, that could be a reason. Shawn Marion has not exactly made it a secret that he feels underappreciated and undervalued at times, at one point even requesting a trade. The change from Marion to Shaq (who, from all accounts - well, except Kobe, is great in the locker room) should have a very positive affect on team morale and team relations in the locker room.

Of course, on the court is where it matters. Everyone seems to be assuming that the offense will take a huge hit, but I'm not so sure. Even when Shaq is in the game, the Suns will still be able to stay fast-paced. Maybe Shaq won't always make it up the court, but if they're shooting in 7 seconds or less that won't matter much anyway. What Shaq does do is make them a lot better in the halfcourt. His presence allows Amare to move to the 4 where he is more comfortable. He also opens things up even more for the potent shooters outside. Plus, with all of the other offensive weapons, you can't really double team Shaq, meaning he could potentially have some very solid scoring nights.

Defensively is the interesting part. Shawn Marion was one of the best defenders in the NBA, capable of guarding any position. Now, the Suns don't really have anyone like that. Who's going to guard the athletic 4 men in the Western Conference? Yes, Shaq provides a big defensive presence at the rim, but you can't really replace a Shawn Marion on the defensive side of the floor.

Now, let me say that I certainly wouldn't have made this trade if I were the Suns. On paper, it seems to make them worse. But looking at it, it's maybe not as senseless as a lot of people are making it out to be. The Suns will still get up-and-down the court and still score a ton of points. But how they respond on the defensive end will be the big determinant on whether this deal will have positive impacts.

What are your thoughts? Are the Suns still a legitimate contender in the West?