In today's NFL, you need to have alot of young talent, some of it that developes, some of it that can produce at the time(you want more of this than the developing players), but you need a solid core of veterans to teach the young guns, and to enstill the teams philosophies on them. You can't buy everything in this league anymore, so you have to rely on alot of unproven, young guys. Also, coaching plays a larger role in the NFL than ever before. Barry Switzer would never win a Super Bowl with New England, he did it because the '95 Cowboys had so much talent.
See Dis! I got boalls! Fahgettaboutit!