Source: Wikimedia Commons.

Outback Steakhouse became famous for its "No Rules, Just Right" attitude to restaurant dining. But investors are far from convinced that everything's just right when it comes to the steakhouse's corporate parent, Bloomin' Brands (NASDAQ:BLMN), which reported earnings Tuesday morning.

Shares of Bloomin' Brands plunged 20% in the first hour and a half of trading this morning and were still down more than 20% as of 2:30 p.m. as investors responded to the company's latest results. Overall revenue rose 9%, and adjusted net income rose about 7.5% after accounting for one-time items both this year and last. But comparable-restaurant sales failed to produce impressive growth, with systemwide comps rising 0.6%. Outback Steakhouse managed to come in slightly ahead of the company average, with a 0.9% gain in comps. But a drop of 1.2% for Bloomin's Carrabba's Italian Grill offset Outback Steakhouse's relative strength. Moreover, with guidance pointing toward a more prominent role for Carrabba's, Bloomin' Brands seems to be signaling that Outback Steakhouse alone can't produce enough growth to keep investors satisfied -- and that's a big part of what's causing shares to plunge Tuesday.

Source: Bloomin' Brands.

What's behind the big drop?
Earlier this year, when Bloomin' Brands issued its report for the first quarter of 2014, the restaurant company blamed flat comparables on unfavorable weather and the shift in the timing of the Easter holiday. Again, solid performance from Outback Steakhouse helped to offset losses from Carrabba's and Bonefish Grill, but Bloomin' expected that expanding to more extensive lunch offerings on weekends would lead to longer-term success.

Today's report, though, showed those initial beliefs to be largely incorrect. Despite improving weather, CEO Liz Smith noted that dinner traffic didn't bounce back as much as the company had expected. Even though expanded lunch brought greater traffic, declines at dinnertime left overall traffic figures flat for the quarter. Moreover, rising prices for food commodities weighed on margins, keeping earnings growth in check.

Yet what really spooked investors today was Bloomin' Brands' cut to its full-year guidance. Although the company expects revenue to come in slightly higher than originally anticipated, the business won't be as profitable, with Bloomin' cutting adjusted net income guidance by 10% to 13%. The restaurant operator also cut its comparable-sales projections by a percentage point and now anticipates flat to 15% growth in comps domestically.

Is Outback Steakhouse getting the attention it deserves?
Perhaps most disturbing to Outback Steakhouse fans is the fact that Bloomin' Brands seems to be stressing its other concepts, even though they haven't performed as well as Outback. The company announced today that it plans to expand Carrabba's Italian Grill into the Brazilian market, with the first new store expected to open in the first half of 2015. Given Carrabba's tepid reception in established markets, it's unclear why Bloomin' isn't focusing more exclusively on Outback in the opening stages of its international expansion.

Source: Outback Steakhouse.

Admittedly, the company opened three new Outback Steakhouse locations in Brazil in the quarter, constituting most of the five new Outback locations that Bloomin' saw open during the quarter. But closures of three Outback locations in South Korea and one domestic location partially offset that growth, and given the difficulties that the restaurant industry faces overall, having so many different concepts to juggle at the same time seems like a recipe for a lack of necessary focus on Bloomin' Brands' best growth opportunities.

After impressive performance following its 2012 IPO, Bloomin' Brands has seen much of the bloom come off its share price recently. Until Carrabba's and its other chains start to outperform its core Outback Steakhouse concept, though, the restaurant stock is unfortunately likely to see its recent losses continue well into the future.