I just did a simple exercise with easily accessed information. Took the cap hit numbers from Miguel and the franchise tag numbers from Wiki. From 2008 until today, Tom Brady has left "at least $21 mil on the table. I took the franchise tag number for QB and subtracted TBs cap hit. Arguably, he is better than a franchise tag level QB, top 3 on a year to year basis, but as a frame of reference, it is worth looking at.
<table border="0" cellpadding="0" cellspacing="0" width="1029"><colgroup><col style="mso-width-source:userset;mso-width-alt:6948;width:143pt" width="190"> <col style="mso-width-source:userset;mso-width-alt:2998; width:62pt" span="9" width="82"> <col style="mso-width-source:userset;mso-width-alt:3693;width:76pt" width="101"> </colgroup><tbody><tr style="height:18.0pt" height="24"> <td class="xl68" style="height:18.0pt;width:143pt" height="24" width="190">
</td> <td class="xl68" style="width:62pt" align="right" width="82">2016</td> <td class="xl68" style="width:62pt" align="right" width="82">2015</td> <td class="xl68" style="width:62pt" align="right" width="82">2014</td> <td class="xl68" style="width:62pt" align="right" width="82">2013</td> <td class="xl68" style="width:62pt" align="right" width="82">2012</td> <td class="xl68" style="width:62pt" align="right" width="82">2011</td> <td class="xl68" style="width:62pt" align="right" width="82">2010</td> <td class="xl68" style="width:62pt" align="right" width="82">2009</td> <td class="xl68" style="width:62pt" align="right" width="82">2008</td> <td class="xl68" style="width:76pt" width="101">
</td> </tr> <tr style="height:18.0pt" height="24"> <td class="xl68" style="height:18.0pt" height="24">Franchise tag for QB</td> <td class="xl67" align="right">$19,953,000 </td> <td class="xl67" align="right">$18,544,000 </td> <td class="xl67" align="right">$16,912,000 </td> <td class="xl67" align="right">$14,896,000 </td> <td class="xl67" align="right">$14,400,000 </td> <td class="xl67" align="right">$16,100,000 </td> <td class="xl67" align="right">$16,405,000 </td> <td class="xl67" align="right">$14,651,000 </td> <td class="xl67" align="right">$13,730,000 </td> <td>
</td> </tr> <tr style="height:18.0pt" height="24"> <td class="xl68" style="height:18.0pt" height="24">Tom Brady's cap hit</td> <td class="xl67" align="right">$14,000,000 </td> <td class="xl67" align="right">$14,000,000 </td> <td class="xl67" align="right">$14,800,000 </td> <td class="xl67" align="right">$13,800,000 </td> <td class="xl67" align="right">$8,000,000 </td> <td class="xl67" align="right">$13,200,000 </td> <td class="xl67" align="right">$17,420,000 </td> <td class="xl67" align="right">$14,620,000 </td> <td class="xl67" align="right">$14,621,320 </td> <td>
</td> </tr> <tr style="height:18.0pt" height="24"> <td class="xl68" style="height:18.0pt" height="24">
</td> <td class="xl67" align="right">$5,953,000 </td> <td class="xl67" align="right">$4,544,000 </td> <td class="xl67" align="right">$2,112,000 </td> <td class="xl67" align="right">$1,096,000 </td> <td class="xl67" align="right">$6,400,000 </td> <td class="xl67" align="right">$2,900,000 </td> <td class="xl67" align="right">($1,015,000)</td> <td class="xl67" align="right">$31,000 </td> <td class="xl67" align="right">($891,320)</td> <td class="xl67" align="right">$21,129,680 </td> </tr> <tr style="height:18.0pt" height="24"> <td class="xl68" style="height:18.0pt" height="24">
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</td> <td class="xl66">Left on the table</td> </tr> </tbody></table>