Searching after the fact. Jim gave us a fishing pole to consider. He wrote...

Don't read too much into that post.

The ratio of the two might not have much meaning over long periods, and comparing the P/B of one directly to the P/B of the other might not make sense.

The idea of the graph was just to see if the current moment (in the context of the recent past) seems to be an above-average or below-average moment to switch horses, if you were thinking about doing so. It's fine for that, but I wouldn't take the reasoning much further.

The reasoning of the graph:
Since they are both firms that are generally valued by a smoothly rising metric (not biotechs), squiggles in the ratio of their prices correspond pretty closely to squiggles in their relative valuation multiples, at least over moderate time frames without discontinuities in value.

With hindsight, in early Feb you'd want to have switched in one direction, and in early April the other direction. Assuming a tax sheltered account.

Jim