The bull case supporting my position in Gap (NYSE:GPS) is reasonably simple. On a consolidated basis, Gap stock is cheap. Ahead of Gap earnings for Q3, on Tuesday afternoon, GPS stock trades right at 9x FY18 (ending January) consensus EPS estimates.

As far as retail stocks go, that multiple is hardly an outlier. Foot Locker (NYSE:FL) trades at a bit over 10x earnings. American Eagle Outfitters (NYSE:AEO), despite torrid performance from its Aerie business, is at 13x, as is Victoria’s Secret owner L Brands (NYSE:LB). Given the pressures in mall retail, and what looks like meager underlying growth for Gap Inc, the soft multiple assigned GPS stock isn’t an enormous surprise.

But investors are missing an important fact. Gap isn’t a mall retailer anymore — at least not from a profit perspective. The company’s Gap and Banana Republic brands, of course, are among the best-known U.S. mall brands. However, those two brands only account for about 40% of total revenue — and an even smaller share of Gap Inc profits.

The story behind GPS stock should be about Old Navy and athleisure concept Athleta. That’s still not the case, however. The headline news after Gap earnings for Q2 was that Gap brand sales disappointed. Gap stock fell despite a strong quarter from Old Navy.

Quite simply, that’s backwards. And Gap stock should show substantial upside once the market figures out why that is. Tuesday’s Q3 earnings report could begin that process – or it could give investors on the sideline another chance to buy GPS before the story becomes clearer.

Gap Earnings Don’t Look Great

Consensus expectations for Gap earnings in Q3 don’t seem to show a company posting torrid growth. The Street is looking for a 4.3% year-over-year increase in revenue — followed by 1.9% decline in Q4.

Expectations for full-year Gap earnings growth look stronger — 17% in Q3, 21% for the year — but the gains are coming almost solely from a lower tax rate and share repurchases. FY19 estimates currently suggest less than 5% profit growth next year — which, too, is likely coming from a reduced share count.

And the market seems to be reacting to those broad expectations, valuing GPS at about 10x earnings and cash flow. Gap stock hit a 13-month low last month and is threatening those levels again ahead of Tuesday’s earnings release. The stock does look a little cheap, perhaps, in the context of mall retail. Bret Kenwell argued in late August that the stock had 30% potential upside.

But given that the Gap brand is struggling and Banana Republic is growing only after years of declines, from a consolidated basis the multiples assigned to GPS stock make some sense — even to a bull like myself.

Look Closer at GPS Stock

But what is happening to overall earnings is that Gap brand profits, in particular, are falling, while those of Old Navy and Athleta are growing. Gap doesn’t break out profits at the individual levels, but last year, it gave a hint in an investor presentation:

Gap may seem like a mall retailer. But from a profit standpoint, it’s not. Individual margin figures, combined with sales data from filings, suggests that Old Navy generates at least two-thirds of overall Gap earnings. And Athleta, which is heading toward $1 billion in sales, supports a reasonable chunk of the $10 billion market cap here, even when valued at a substantial price-to-revenue discount against larger peer Lululemon Athletica (NASDAQ:LULU).

Meanwhile, Old Navy and Athleta are expanding while Gap brand and Banana Republic are shrinking. Over time, profits are going to grow, simply because an increasing proportion of sales will come from the “good” businesses.

That shift also matters in terms of the valuation of Gap stock. Old Navy is a model similar to off-price retailers like Ross Stores (NASDAQ:ROST) and TJX Companies (NYSE:TJX). Its sales growth, save for a blip back in FY16, has been just as good. And if an investor values Old Navy even at a reasonable discount to ROST and TJX, Old Navy’s value is more than that of Gap Inc as a whole. Add in Athleta and there’s easy 25% upside — even ignoring Gap brand and Banana Republic.

Will Management Push Gap Stock Higher?

What’s interesting ahead of Tuesday afternoon’s report is that management has the ability to make that bull case more forcefully. Again, it’s only even mentioned brand-level margins the one time. Even on the Q2 call, Peck seemed more interested in fixing the struggling brands than highlighting the strong ones.

Were Gap to break out segment-level performance, the bull case would become much clearer — and Gap stock almost certainly would rise. One analyst has even publicly called on the company to change its name to Old Navy.

For whatever reason (I’m guessing competitive concerns about detailing Old Navy’s margins), Gap hasn’t done so. But it likely will at some point. In the meantime, I’m happy waiting, particularly with a 3.8% dividend yield.

And so Q3 earnings, barring a notable divergence from expectations, may be more about the conference call, and the reaction, than the numbers themselves. If Gap management starts better highlighting the story, then investors should look to jump in ahead of the key holiday season. If not, that leaves an opportunity to buy Old Navy at a nice discount — and wait for the story to turn.

Yes, either way, I think GPS is a buy; in fact, I think it’s one of the most attractive stocks in the entire market. And I believe it’s largely up to management to choose when, and how, more investors realize that fact.

As of this writing, Vince Martin is long shares of Gap Inc. He has no positions in any other securities mentioned.