That's a great point, as we are down to two eligible far arms, now: Uberstine & Samaniego, neither of whom are SP'ers.
That being said, I'm not counting on Early to return or Eyanson to pitch in the bigs, this season, so trading one of them or Witherspoon would only affect the future.
The future is important, but we can add pitchers, this winter or next to replace who we trade.