Not really an expert, but before the reboot it was just accepted that Flash can't go full blast all the time, because stuff like running faster than Death and vibrating molecules around things is a strain on him. Plus most of his crazy feats come from him fighting guys who are equally ridiculous.
After the reboot they nerfed Barry's powers considerably and in addition he has to relearn to use them. Manapul also seem to be making his more street-level villains stronger. For example Captain Cold was just a guy with a freeze ray, but now he has actual ice powers, part of which includes slowing down Flash considerably whenever they're close.
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