Just a little over a week ago, the sports world was shocked to hear the news that Buccaneers Guard Ali Marpet retired from the National Football League after just seven seasons. On Monday, Colts Tight End Jack Doyle announced his retirement after nine years of professional football. You may say, "Nine years? That's a long time." Maybe so; however, when you think of retirement in terms of age, Marpet (28) & Doyle (31), you may gain a different perspective. Add Doyle to the recent list of younger NFL veterans to retire in the last decade: Luke Keuchly, Rob Gronkowski, Andrew Luck, Calvin Johnson, Chris Borland, Patrick Willis, and Eugene Monroe.