Like others have said, you need to do a combination. Young guys, plus older vets who can teach them. Look at our positions, we have Peters, young guy who's very talented for our corners, and then Shields and Talib are older guys who can teach young talent (and any potential rookies) some old vet secrets.
Our WR group has someone like Woods.
Our OL has Whitworth to teach the young guys. etc.
When you fill your team with old FA on one or two year deals (like we were doing with Spags and all them) that's when you never really get better, because you're always replacing. But we have young talent at each position. QB, RB, WR, CB, S, OL, DL, we mostly need to get depth at OT, and fill out our LB.