I'm not sure that I'd call a west coast team (until the time change halfway through the season) traveling to the east coast "a given," especially with a low 4 point spread, but I'd agree that ARZ looks like it
should win.
That said, I'm very leery of betting this so called "obvious" game, even with the stark difference in talent and circumstance. According to BetLabs and their system, since 2005, when an ATS winner from a previous week is coming west to east, they are only covering about 29% of the time. The number gradually gets lower the further they move across the country, which is why it's so low by the time they get east. It's not quite as dramatic for a west coast team (coming off an ATS cover) who is traveling to say, the mountain time zone (38%), but it's still not good.
If you're considering ARZ, it may be a good idea to buy yourself a full point and take it down from -4 to -3, just in case they eek out a late victory via FG, or BUF scores a garbage time TD down 10. Another important unknown variable would be the changing of OCs. A scaled down playbook may help/hinder Tyrod Taylor. Finally, there's the question of how much Watkins may play. Of course, all of this analysis may be pointless if you simply believe that the Bills just suck.