In that context I agree, I could split hairs and say Helg plays that role and his issue is more ability then experience, but Quincey certainly has that experience advantage over Santini, who certainly plays that style, and hopefully has the talent to at some point fill that role.
I think we pretty much are in agreement. I probably come across as favoring veterans over youth, but that isn't always the case. If Seth had demonstrated an ability to be that solid shutdown defenseman, then I (and probably Shero, Hynes, and company) would have more confidence with him filling that role, but in his stints in the NHL he's struggled a lot with getting trapped in his own zone.
It's hard to go into the year counting on Santini to fill that role at the NHL level when we've only see him play one NHL game, but hopefully Santini can grow into the solid shutdown defenseman. I'm not sure if the plan is to have him in the AHL or the NHL this season, but this was a short term signing, so long term I don't think it impacts Santini much.
The biggest value of experience for me is that the person has hopefully demonstrated a track record of ability to fill a given role on a team (as well as the leadership dimension or steadying young players).