He's signed to a minor-league contract, not a major-league contract. If and when he gets called up, he'll be added to Yahoo then.
Check out my list of preseason sleepers and breakout candidates on my new blog. There is no spam or pop-up ads, just a blog that has lots of baseball stuff on it and will be updated daily. Hopefully it will give you something to think about.
Here's the link, and feel free to post comments. Cheers!