On paper Washington should beat Arizona, I don't fancy being David Johnson going up against a healthy Redskin front four as it is starting to look nasty with Allen and the aptly named Payne waiting for him.
I wouldn't be surprised if Cleveland somehow beat Pittsburgh in the first week, I don't think it's beyond the realms of impossibility. The cleveland team coming out in 2018 has so many changes in the starting lineup from the 2017 team the Steelers could be in for a surprise as they have no game film to study. The Steelers last year didn't look all that and like you rightly pointed out they were sneaking a lot of their games.
Miami have a tough opening game against the Tennessee Titans. I'm not sure they will be able to stop Mariota and Murray to be honest. I take the Titans winning that one 21-17.
Below is the latest odds, I'm surpised to see the Steelers at 7/1 and the Los Angeles Rams at 20/1, I would have had those two reversed. Looks like the Redskins and Dolphins are no hopers at 80/1.
New England Patriots: 5/1
Pittsburgh Steelers: 7/1
Philadelphia Eagles: 7/1
Green Bay Packers: 12/1
Minnesota Vikings: 14/1
New Orleans Saints: 16/1
Atlanta Falcons: 18/1
Houston Texans: 18/1
Dallas Cowboys: 20/1
Jacksonville Jaguars: 20/1
Oakland Raiders: 20/1
Los Angeles Rams: 20/1
Seattle Seahawks: 25/1
San Francisco 49ers: 25/1
Los Angeles Chargers: 25/1
Kansas City Chiefs: 25/1
Carolina Panthers: 30/1
Denver Broncos: 30/1
Baltimore Ravens: 40/1
Tennessee Titans: 40/1
Indianapolis Colts: 40/1
Detroit Lions: 50/1
New York Giants: 60/1
Tampa Bay Buccaneers: 60/1
Arizona Cardinals: 80/1
Washington Redskins: 80/1
Miami Dolphins: 80/1
Buffalo Bills: 80/1
Cincinnati Bengals: 100/1
Cleveland Browns: 100/1
Chicago Bears: 100/1
New York Jets: 100/1