Ok, I broke down Ryan Tannehill's "Passing Yards per attempt" by "Air Yards per attempt" and "YAC per attempt". It still looks like an improvement.
2015:
- Air Yards per Attempt: 4.51
- YAC per Attempt: 2.99
- Total Yards per Attempt: 7.5
2014:
- Air Yards per Attempt: 3.53
- YAC per Attempt: 3.37
- Total Yards per Attempt: 6.9
2013:
- Air Yards per Attempt: 3.76
- YAC per Attempt: 2.94
- Total Yards per Attempt: 6.7
2012:
- Air Yards per Attempt: 4.01
- YAC per Attempt: 2.79
- Total Yards per Attempt: 6.8
http://www.sportingcharts.com/nfl/stats/quarterback-air-yards/2015/
http://www.nfl.com/player/ryantannehill/2532956/profile
Additionally, Kenny Stills' 17.4 yds/reception is the highest season average for any Miami receiver during Tannehill's 4 yrs (for receivers with 10+ catches in a season).