Since 2010, there have been six teams (out of seventy-two) that have made the playoffs with a negative point differential (none in 2015). It's not an easy task to not score more than your opponents and make the playoffs.
Under Jeff Fisher, the Rams have actually had a respectable point differential from year to year, even when they were trotting out QB's such as Shaun Hill, Austin Davis, Kellen Clemens, Case Keenum and your Uncle Rico:
2012: -49 (22nd)
2013: -16 (17th)
2014: -30 (21st)
2015: -50 (19th)
So, the key questions are: will a rookie Jared Goff, a healthy Todd Gurley, a developing Tavon Austin, a young but talented OL and a healthy defense be what takes the Rams over the top, or will they need more?