As I mentioned in the other post, to give fans an idea of the power level of The Black Flag, I compared his fighting ability and how he would match up with someone like The Hulk. Now I want to point out the flaw in Flag's ability. Although Flag is a great fighter on his own, his enhanced abilities require a certain amount of focus and concentration. Just like lifting a heavy couch, Flag must take that moment to focus on the task at hand, at which point the Super Adrenaline will kick in and allow him to do what he needs to. But an opponent like Spider-Man would be almost impossible for Flag to defeat. The guy is just too formidable. Spidey is incredibly strong, nowhere near the Hulk level but far beyond guys like Cap and Black Panther.
Add to that his spider-sense, reflexes and annoyingly bad puns meant to distract you and Flag would simply not be able to adapt to Spider-Mans fluid, agile means of combat. Multiple opponents would cause the same problem, Flag is a one-on-one type of guy and just doesn't do well against a group.