Saints expected to be very interested in former Packers/Cowboys HC Mike McCarthy [McCarthy will interview early next week]

It is relevant for a couple of reasons:
You can't discount the Cowboys' record the last 5 years, which was not 4 NFCCG's and a SB (which was 2 WC losses and 1 divisional loss) and just go back 7 years to the record with the Packers for convenience.

Then fact that no HC has won a SB with 2 different teams, is just that.

So, if the expectation is to flounder in the playoffs and don't win a SB, then fine.
7 SB winning coaches have managed to make it back to the SB. With a different team. Odds are it will happen again, and someone will get that win at some point.

Anyway, it's still irrelevant because what history says doesn't determine how he'll do with the Saints.

As for his time with the Cowboys, he led a Dak quarterbacked team to 3 consecutive 12 win seasons prior to last year's injury riddled season. That's pretty impressive in spite of their playoff results. The guy made the playoffs 13 out of 18 seasons with 2 different teams.