I think they are really close. At times last year they looked like one of the best teams in the NFL. Then the defense and o-line fell apart. I think if you could play last season over again there would be a pretty good chance that team would do better than 8-8. Bad coaching, bad "breaks," unfortunate injuries, whatever. Yeah some of this will occur every year, and every team's fans probably feel the same way. So, I'm not saying the Dolphins got screwed last year, but there will be a time when these kinds of things go our way. That can be the difference between 8-8 and 11-5.
If we can somehow get the defense and o-line to play like they did in the first half last year, plus another year in Lazor's system with Tannehill's expected growth, i think the Dolphins certainly CAN contend this year. Whether they will or continue to "beat themselves" as they seem to have been doing forever remains to be seen.