Stagnation is a very real thing.
They aren't necessarily a problem individually, but they have gone 8 years without any kind of success and are still in the same roles. Kopitar has faded from an arguably top 10 center to a top 25 or so. Doughty still has plenty of rubber on the tires. 8 seasons is an eternity in sports, a very, very long time to keep the same formula in place without results.
The question is how long has your team gone on unsuccessfully without making changes to the core pieces of its lineup?