The leaves fall and the Giants rise. It happens every year … except this one. In coach Tom Coughlin’s previous nine seasons, his Giants at the halfway point were 5-3 twice, 6-2 six times and 7-1 once for a first-half record of 53-19 — a winning percentage of .736. Their second-half swoons were as predictable as frost on the lawn, and the unexpected Super Bowl runs in 2007 and 2011 were sights to behold. In Coughlin’s 10th anniversary season, instead of presenting him with the traditional tin or aluminum gift or the more modern diamond jewelry, a handful of rocks have been dropped at his doorstep. The louder he preached no turnovers, the more the Giants committed them. The more he insisted “Finish!’’ the Giants caved in during the fourth quarter. The 0-6 start was the worst for the franchise in 37 years and the 2-6 record at the bye week looks only marginally better. If not for the mediocrity within the NFC East — where the 4-4 Cowboys sit atop the pack — the Giants would be in complete wait-‘til-next-year mode rather than just two games out of first place. Still, 2-6 is 2-6, a well-earned last place and in serious danger of dropping out of relevance if they do not get on a major roll in the second half.