Yeah I feel like Squire's adjustment to the stat I'd seen - that teams are 15-9 when trying to win for the third time - suggests it's not that tough. And the thing you posted adds that the home team was 12-5 at that point.
I don't think overconfidence is an issue given the past month. Injuries or not Eagles lost 2 of their last 3 and struggled against the Bears. Giants on the road is really their only recent great win, and arguably Cowboys, Packers and Giants are the only great wins over a 12 game stretch (with just the Vikings and the surprise Jags as two others, even if the Commanders were decent).
Before the playoffs started I was surprised that the Eagles were still the favorite in the NFC but that was just based on seed and record, I believe the 49ers are now (and the two AFC teams ahead of both).