September is a difficult month for WWE. With the start of Monday Night Football, RAW's ratings take a serious hit. Plus, the fanbase at large go through a major post-SummerSlam hangover that slightly subsides during Survivor Series, but doesn't go away entirely until the Royal Rumble. This generally results in a stretch from September to January where WWE seem creatively stagnant and directionless. With none of the major angles heading into WrestleMania building until the Royal Rumble, fans are forced to sit through a lot of filler that feels like an uninspired rerun most of the time.
However, such a stigma can result in quality getting overlooked. While September has never been a banner month for quality PPVs, the fact is, there's still been plenty of great stuff to come from it. That doesn't include the obvious classics such as Shawn Michaels vs. Mankind or Cena vs. Edge in a TLC match. There have been some truly standout matches that have been swept under the rug probably because they took place in September instead of at a bigger PPV.
Not all of these matches were instant classics, but all of them are ones that aren't talked about enough, or feature performers who don't get enough credit.