It does if the explanations are contradictory. In this case this means one of two things: 1) The "first bus collects delay" theory is responsible for a part of

It does if the explanations are contradictory. In this case this means one of two things: 1) The "first bus collects delay" theory is responsible for a part of the difference between the data and the model, after all there is some. 2) There is another mechanism at action that statistically reverses the effect of the "first bus collects delay" theory, not necessarily in the same bus runs. Number 1) is coherent with Occam's razor.