If this was h2h I would be inclined to accept, but the fact that this is a roto league makes me think reject. I only say this because balance is key in roto. If you already have a solid pitching staff, there is no need to make a trade to upgrade, especially when you have to downgrade your 2b. However the trade might put you at the top of various pitching categories, and you could always trade away a pitcher in the future.. how does your rotation compare to the rest in the league as it stands?
I like your staff even without Santana, and I wouldn't trade an injury risk player for a non-injury risk player unless I was getting blown out of the water. Barring the injury, its close to break even, so I wouldn't make the deal.
I don't like it. Phillips is a roto stud, and I feel that you might be overpaying for Polanco's nice start (although he might end up having a decent season).