Where are you getting those numbers from? These are all time percentages:
NFL Career Field Goal % Leaders | Pro-Football-Reference.com
<table data-crop="50" data-freeze="20" class="stats_table nav_table"><tbody><tr class=""><td align="right">1.</td> <td>
Mike Vanderjagt </td> <td align="right">86.466%</td> <td align="right"> 1998-2006 </td> <td align="right">2TM</td> </tr><tr class=""> <td align="right">2.</td> <td>
Nate Kaeding </td> <td align="right">86.190%</td> <td align="right"> 2004-2012 </td> <td align="right">2TM</td> </tr><tr class=""> <td align="right">3.</td> <td>
Robbie Gould (32)</td> <td align="right">86.029%</td> <td align="right"> 2005-2013 </td> <td align="right">chi</td> </tr><tr class=""> <td align="right">4.</td> <td>
Steven Hauschka (29)</td> <td align="right">85.965%</td> <td align="right"> 2008-2013 </td> <td align="right">3TM</td> </tr><tr class=""> <td align="right">5.</td> <td>
Rob Bironas (36)</td> <td align="right">85.663%</td> <td align="right"> 2005-2013 </td> <td align="right">oti</td> </tr><tr class=""> <td align="right">6.</td> <td>
Stephen Gostkowski (30)</td> <td align="right">85.597%</td> <td align="right"> 2006-2013 </td> <td align="right">nwe</td> </tr><tr class=""> <td align="right">7.</td> <td>
Shayne Graham (37)</td> <td align="right">85.467%</td> <td align="right"> 2001-2013 </td> <td align="right">10T</td> </tr><tr class=""> <td align="right">8.</td> <td>
Matt Bryant (39)</td> <td align="right">84.818%</td> <td align="right"> 2002-2013 </td> <td align="right">5TM</td> </tr><tr class=""> <td align="right">9.</td> <td>
Phil Dawson (39)</td> <td align="right">84.461%</td> <td align="right"> 1999-2013 </td> <td align="right">2TM</td> </tr><tr class=""> <td align="right">10.</td> <td>
Connor Barth (28)</td> <td align="right">84.167%</td> <td align="right"> 2008-2013 </td> <td align="right">2TM</td></tr></tbody></table>
You were looking at 1 year numbers, not career. The highest is career percentage is 86.4% (minimum number of kicks attempted of course)
For instance last season Matt Prater lead the NFL with at % of 96.2%, but for his career he is 81.6%