The headline should be: "Great Behavior Is Linked to Time in Quality Day Care".
Poor behavior in day care graduates is only ascribed to those children in substandard day care. I am frankly becoming quite unnerved by the volume of messaging attacking daycare as a general concept. Given the necessity of dual-working parents across most income demographics, it's not a useful construct.
My two children are successful graduates of daycare. I think daycare has provided additional stimuli and social benefits that we could not have provided under any other scenario.