I, too, prefer proven over potential. With that said, i'd definitely move RNH. He and Yak havethe hype, so you should be able to capitalize there. If you can't find a worthy partner, I'd go with Parise and Yak to sure up your wingers, incase Giroux loses his W eligibility. Staal would be my last keeper over RNH. He has too much grit to his game not to keep. He and Parise, when not scoring goals, will add to your other cats. Even Giroux can be chippy. Yak has a better frame than RNH, so he'll likely contribute more elsewhere.
IMO, last thing you want to do is have Giroux end up being a Center and you let Yak or Parise go while keeping RNH. You would have too many Cs. Even if Giroux was a winger only, i'd rather have more wingers than a C. If this ends up being the case, I guarantee someone would seek you out in a trade for a winger.

Giroux
Parise
Staal
Yak

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League: Yahoo 20 Team Dynasty, H2H (4C, 8W, 6D, 1G)
Cats: +/-, FOW, A, G, GWG, PPP, SHP, SOG, S, SPct, W, GAA

C: Kopitar,Nyquist,J.Staal,Strome
W: Atkinson,Benn,Brunner,Huberdeau
Iginla,Kessel,Seguin,Selanne
D: Beaulieu,DeKeyser,Despres,D.Hamilton,Leopold,Salo
G: M.A.Fleury
Bench: B.Bennett,B.Gordon,Petrovic,Stalberg - J.Bernier, J.Howard
Prospects: Andrighetto,V.Arvidsson,G.Carey,Filatov,Kabanov,Kuhnhackl,Omark,R.Schwartz
Shalunov,Stransky
Clendening,Deslauriers,Gauthier-Leduc,J.Morrow,R.Murphy,Postma,Reilly -- P.Bartosak,N.Lundstrom,J.Olkinuora,A.Wilcox