Can Travis Kelce, the three-time Super Bowl champion tight end for the Kansas City Chiefs and the fiance of the world's biggest pop star, Taylor Swift, turn around Six Flags Entertainment, North America's largest regional amusement park operator. Now, if you asked me that question a little over a month ago, I would have said, "What are you smoking here?" But because you got to believe it or not, this is now a real question investors are grappling with. See, Six Flags as we know it today was created last yea ...