Quoting: ricochetii
That's different than his goals, points, and possession numbers being down. It's not as worrisome if you look beyond raw numbers, which any team will do.
Here is the ranking of points leaders by defensemen over the age of 32 for this season: Letang (6), Burns (13), Goligoski (41), Giordano (48), Ryan Suter (63), Erik Johnson(75), Braun (92), Jeff Petry (117), Anton Strålman (125), Nick Holden (124), Alexander Edler (135), Marc Staal (145), Marc-Edouard Vlasic (153), Andy Greene (158), Jack Johnson (161), Zdeno Chara (164), Jordie Benn (204), Kris Russell (211) .
The point I'm trying to make is that offense first defensemen don't have an exceptionally long shelf life, and when they do their numbers tend to go lower as they get older.