Read the full letter at WOTC's site:
An Open Letter to Spike : Daily MTG : Magic: The Gathering
Here's a quote
You might wonder at this point why I say we can't know exactly what our Magic metagames look like. There are only a handful of Magic developers, and another few handfuls of people who help with Constructed and Limited playtesting. If that small group of people knew exactly what a Magic metagame looked like, it would take barely any time for the millions of you Spikes out there in the world to figure it out, and that would be no fun at all for you. I know it's hard to keep perspective while you're actually playing a game of Magic—I was one of you before I started working here, and all I cared about once a game started was beating my opponents. However, we all play games because they're fun, and it's more important to us that you enjoy our game than it is that we understand it perfectly. So as it is, we're always doing a little bit of educated guessing.