KANSAS CITY, Mo. — Patrick Mahomes’ 13 career playoff victories as a starting quarterback are tied for sixth in NFL history. With the next one — the opportunity arrives with Sunday’s AFC championship game at Baltimore — he’ll move into a third-place tie on that list. That’s amazing enough. But consider this has occurred in Mahomes’ first six years as a starter. The leader, by far, on the victory list is Tom Brady. His 35 playoff triumphs more than doubles second-place Joe Montana (16). And Brady won Super Bowls in his first three postseason appearances with the New England Patriots. But it too…