Why is trading a pick for a player a problem if that player is better than anything we can reasonably hope to take with that pick in the first place? You're trading a degree of longevity for a guarantee of success.
Age and cap hit are factors. Granted, we have a ton of cap space, so that doesn't apply to us in this instance. But having said that, we've already invested a significant amount in the position already (Trumaine).
The draft capital is where my concern lies...every week we talk about the holes on our roster. We can't fill them all in FA, we need draft picks. If we were a contender, i would love to bring in Peterson. But we're not, so it doesn't make sense for us right now.