Niskanen is an upgrade, played over 20 minutes a night on the 1st pair in the last five Cap playoff runs. And that was under two different HCs. Lot of trust there.
He admits he's not the same player he was in his prime, but his role won't be to carry the defense, but to be a stabilizing partner and coach on the ice with the young defensemen we're rolling this year, Provorov, Sanheim, Myers, Morin and maybe Friedman. Ghost can't play that role b/c his talent is sui generis, his fundamentals are a bit shaky.
Gudas was fun, but he was also a 3rd pair D-man (15 ES minutes a night last two years), and he's was efficient, but with a very funky style. Did work hard to curb his psychotic streak. Good clubhouse guy but I've never seen him as a mentor type.