Note: there's a good discussion of positional adjustments in the comment thread. The numbers I present don't tell the whole story.
-----
So I'm late to the party, here. If it helps, that was deliberate - this being the first day of anything, I didn't think the position switch was sufficiently meaningful to warrant a post. But I've gone back and forth on it, and now here I am.
I won't bother repeating in detail what others have already said. You can read Dave's take at USSM, Jon's first and second takes at PBNW, and Shannon Drayer's take as well. They've already been very thorough in their coverage of the first real story of the spring.
The main point of concern being raised is lack of experience - practice and minor leagues aside, Figgins has never played second as more than an occasional position, and Lopez only has 25 innings of ML time at third. It seems strange, then, to switch them, because Figgins is great at third, Lopez is okay at second, and all of their experience at their respective positions has to count for something. How reasonable is it to expect them to be able to make seamless transitions to another spot?
It is an excellent point. Experience at a defensive position can matter a lot. There are parts of playing second and parts of playing third that you can't learn if you don't experience them firsthand, and experience them over and over. Lopez, one imagines, is better at turning the double play than Figgins is right now. And Figgins, in turn, is probably better at, say, charging a bunt or throwing across the diamond.
But what if both Figgins and Lopez take to their new positions with ease? What if? This is all just an experiment, after all. There's no commitment. That's why they're trying it out, and trying it out so early. Lopez has the body of a third baseman while Figgins has the body of a second baseman, and the team wants to see if that means anything.
Using stats from The Hardball Times, here are the league average balls in zone per season:
Second Base: 425 balls in zone
Third Base: 334 balls in zone
Over the last three years, the Mariners have averaged 445 BIZ at second and 336 BIZ at third. And while third basemen make more out-of-zone plays (OOZ) than second basemen do, the point remains clear - second basemen get more play opportunities than third basemen.
I wonder if this isn't at the very heart of the matter. Chone Figgins is a better athlete than Jose Lopez. He's clearly the better defensive player at his position. He has more lateral range. If Figgins can play second as well or better than he can play third, and if Lopez can handle the hot corner without embarrassing himself, suddenly it might make sense to bump the better defender to the more active position.
Don Wakamatsu made an interesting decision today. We'll see if it means anything going forward. I'm guessing that, come season time, Lopez and Figgins will be back at their normal positions. But now is the time to experiment. We know Lopez can handle 2B and Figgins can handle 3B. They don't need much practice to get up to speed. What if they can switch? What if the team can get the better glove to the more active position? What if it turns out that Figgins is better suited for 2B than 3B, or that Lopez is better suited for 3B than 2B? I'll leave it to the Mariners to determine whether or not this'll work, but I absolutely don't see the harm in trying to find out.