I'am aware of the "Why is the Flash not unstoppable" question but it does not answer the question for the 2014 TV-show.
Here we see the following very often:
Flash arrives and stops and talks to his opponents, often giving them time to shoot at him or invoke environmental effects that harm him. Perhaps in the first season we could argue that he is overconfident and unexperienced, but later in the show this argument does not hold, I think.
He has to "distract" them somehow with some clever trick because he can't get near them (Why? With his speed he can be behind them, disarm them and/or knock them down before they can even "fire" once at him.)
When they are "distracted" he does exactly that. In a split second he just disarms them or knocks them down.
Yes. If an opponent creates conditions that harm or hinder Flash BEFORE he arrives, it makes sense. If the opponent has super fast reflexes (like Flash himself) so he can shoot and hit him even when speeded, it makes sense. If the opponent is invulnerable and the flash when trying to knock him out hurts himself it makes sense. If the flash is surprised by the opponent and not in speed mode, it makes sense.
But we often see opponents that shoot on him with some weapons or abilities and while they don't seem to have super fast reflexes and moving, Flash isn't able to get near them and just disarm them or knock them out.
This especially is obvious in some encounters with Captain Cold. It should be no problem for Barry to disarm him and get his gun in the moment he arrives before Captain Could could even think of firing at him (later he has a dead man switch at his could gun that could in some situations prevent this).
Another example is his encounter with Dr. Light. He has to move so fast that he creates several images of him where Dr. Light fires on. Then he is able to attack her from behind and knock her down. There shouldn't be any problem doing this without the false images.
On other occasions he has no problem even with warned opponents. When he is blackmailed to let his two opponents beat him to death (otherwise several bombs will kill 100 children) his team succeeds to disarm all the bombs. The villains (who in the past were a match for him even without the other) notice that (and even say "Oh oh") and in the next moment one is bound and the other nearly beaten to death.
So is it just very very bad writing or is there any theory why Flash has problems to handle such opponents without difficulties?