Why Washington's cruiser group could not beat Yamato by daylight

Could USS Washington and a cruiser group defeat Yamato, a Kongo, Atago, and four destroyers in daylight near Guadalcanal?

No; Japanese heavy-gun and torpedo superiority makes the stated daylight formation overwhelmingly stronger unless visibility radically changes the engagement.

In clear daylight, Yamato can concentrate on Washington while the accompanying Kongo and Atago engage the American cruisers. Japanese destroyers face no opposing destroyer screen and can prepare torpedo attacks without equivalent pressure. Washington's 16-inch/45 guns remain dangerous, but the panel distinguishes them from the more powerful 16-inch/50 and does not see them overcoming the force imbalance. Thick fog and a radar engagement at range might change the geometry, but that is no longer the proposed daylight battle. Under the stated conditions, the American group would be destroyed rather than repeat a Guadalcanal-style ambush.