Gap's business has been choppy for several years. 
Sales fell 5% in the first quarter because of declining mall traffic and fashion misses. 
Even a booming online business hasn't been enough to stabilize sales at the brand. 
This chart by JPMorgan analysts Brian J. Tunick and Bilun Boyler illustrates why Gap has trouble being consistent. 
The chart shows where apparel retailers rank in terms of fashion and value.
gap chart fashion brands
J.P. Morgan
In every category, Gap is simply average. 
The company isn't the cheapest, like Old Navy and Uniqlo. It isn't renowned for its basics like Everlane, or super-fashionable like Zara.
"Another ongoing concern around the Gap brand is where it fits in the fashion-value equation and who the core customer is, as the product and pricing for the brand has been inconsistent and confusing over the past decade," the analysts write. 
Gap will have to work on defining its identity to get fickle shoppers in stores.