Commendations are nice concept in theory but completely fall apart in practice and are practically worthless.

People give comms for the strangest reason that have nothing to do with thinking that player was a especially valuable during the run.
And harsh as it sounds but most players wouldn't recognize good gameplay if it slapped them in the face with a 10ft pole with fancy lights and sound effects. That RDM/ SMN that silently ressed without some obnoxious 5 line macro, the tank that spot healed someone with vuln stacks before an aoe and saved them from dying, the phys ranged/ melee that had Arm's Lengths & Bloodbath ready when they had aggro or the tank went down, a well-timed and aimed Rescue that prevented a death, the dps that just deleted pulls, the healer that carried most of the healing without ever dropping dps, are all players that will likely go unnoticed.
People comm for exp, for glam/ name/ race etc but rarely do I see well-deserved comms for someone that played well.

Comms are and always will be a terrible metric for gauging someone's skill or ability to be a good mentor and it's best to be aware of that.