First, I think Oog, the actual first discoverer would disagree.
The Pacific Northwest has the Japanese current sweeping things from Japan. Parts of temple gates, glass net floats and other things including the recent boats and floating piers have been found from BC to Southern Oregon. Why not a boat full of storm driven fishermen?
The Chinese could have easily used this same current to take them to America.
And some Chinese may have made it here, but were lost at sea on the way back to China. Sailing the oceans was dangerous business back then!