NHL General Managers have to tailor their deals (or non-deals) around player needs. In other words, on this day, an NHL GM is only as good as his word.
Chara 45, and Greene 39, are nearing the end of their respective NHL careers, especially the former. So, it's understandable that neither man wanted to be moved in what most likely could be their final NHL season. To a man like Lamoriello, it meant more to keep his word than it did to acquire assets to help his team.
Opinion: If you know me, you know I call for the destruction of the "old boys club" that seems to still have a stronghold in hockey today, but, in this case, Lou Lamoriello acted with grace and class towards his veteran leaders by doing exactly as he said. In hockey, your team's need usually comes before the individual, not in this case, and that was refreshing to see.