As Wall Street looks ahead to United Airlines' (UAL) - Get Report scheduled June 21 update on earnings initiatives, Wolfe Research analyst Hunter Keay is suggesting potential changes to the carrier's route structure.

In a report issued Friday, Keay said United could move routes from Los Angeles International Airport, a congested airport where no carrier has been able to build a sizable hub, to San Francisco International Airport, where United's hub is the best on the West Coast.

Additionally, Keay suggested that United may want to continue downsizing in Cleveland, where it closed a hub in 2014. United now offers about 50 daily departures from Cleveland.

United is under pressure because it has generally underperformed its rivals after completing a merger as the airline industry consolidated in the early part of the 21st century. Delta (DAL) - Get Report merged with Northwest in 2008, United merged with Continental in 2010 and American (AAL) - Get Report merged with US Airways in 2013.

United shares closed Monday at $49.53 and are down 22% year to date, compared with a 26% year-to-date decline by American shares and a 19% decline by Delta shares.

In his report, Keay analyzed various carriers' 2015 yield performance by market.

Yield measures the average fare paid per mile and is calculated by dividing passenger revenue by revenue passenger mile.

In 2015, as a decline in fares followed the decline in fuel prices, all six of the largest carriers reported negative yield. American yield fell 14% (due primarily to rivals' capacity expansion in Dallas), JetBlue yield fell 6%, Southwest yield fell 5%, United yield fell 4%, Delta yield fell 2% and Alaska yield fell 1%.

Regarding Cleveland, Keay wrote that United showed a 13% yield decline in its third-tier markets, with the tier based on the number of passengers carried. He said the primary reason for the relatively large decline "is ultra-low-cost carrier growth in places like Cleveland, which United dehubbed in 2014 and {which} was subsequently backfilled by Delta and ultra-low-cost carriers, though United still flies a few routes to Cleveland."

Overall, United has faced more ULCC growth than either American or Delta, Keay said. Competitive ULCC capacity in 2015 represented 12.4% of capacity in United's domestic network, compared with 6.7% in Delta's network and 6.2% in American's, he said.

"Has enough been done in Cleveland and are more cuts necessary in places that aren't necessarily strategically imperative but also weak, like LAX and Dulles?," he asked.

In a controversial 2014 report, Imperial Capital analyst Bob McAdoo urged United to close the Dulles hub and move the trans-Atlantic flying to Newark, N.J. 

"Today the Dulles hub is the smallest in the Northeast, carrying fewer passengers to Europe than Newark, than Delta at JFK or American Airlines/US Airways in Philadelphia," wrote the highly regarded McAdoo, who is now retired. Newark, by contrast, is the  largest.

Regarding California, Keay wrote that San Francisco is obviously a better place for United to do business than Los Angeles (LAX), where both Delta and American seek to grow. He also noted that United has benefited from pulling out of New York's John F. Kennedy International Airport and adding capacity between Newark and California.

"Things are likely to get worse before they get better {at LAX}," he said. "So why not, on a small scale like what United did with the JFK to Newark shift, move assets from LAX to SFO? All else equal, we'd be supportive of something like that."

United's first-quarter earnings call in April was disastrous and is best recalled for a question by JPMorgan analyst Jamie Baker, "Does mediocrity suffice?" Keay, meanwhile, declared, "I think it has been one step forward and one step back for United over the last four years."

During that call, Keay raised the possibility that United ought to consider shrinking, asking, "Is United too big?" He asked whether the carrier requires "major surgery to the network, asset or real estate divestitures, or structural overhaul?"

In response to the barrage of critical analyst questions and comments,  CEO Oscar Munoz offered few specifics, rather declaring "allow me a little more patience" and deferring answers to the investor call that is now scheduled for June 21.

Two weeks remain.

his article is commentary by an independent contributor. At the time of publication, the author held no positions in the stocks mentioned.