The second season in the PL is always difficult for promoted teams.
2010-2011 - Birmingham went down in their second season (Wolves finished 17th and were relegated the following season)
2012-2013 - QPR were relegated in their second season
2013-2014 - Norwich relegated in their 3rd season...
I think what the season did show is that there is a bit of a soft underbelly in the team - that when it came to the crunch some players seemed to bottle it and the confidence ebbed.
One game I can think of - in January Brighton were 2-0 against Fulham after 17 mins and lost 4-2. I think the rot...
The longer you survive in the PL the better your chances are of not getting relegated - particularly if you survive the second season.
Norwich and Sheff Utd will be favourites to get relegated next season - and whoever wins the play-offs. If Villa get promoted they probably have the best...
There have been several teams that were dire the entire season and still survived - QPR about 8 years ago - Wigan the year before that - Hull were brutal one year and survived, they played better the following season and got relegated.