It seems clear that Oscar Munoz's tenure as CEO has been good for United Continental Holdings Inc. (UAL) - Get United Airlines Holdings, Inc. Report .

Labor relations are far better. Operations are much improved. President Scott Kirby is fixing the network. Share price performance has been good. The mess at Newark Airport was cleaned up. Under pressure, United addressed an ancient overbooking/compensation protocol.

But one problem remains: United's financial metrics still trail rivals' financial metrics.

That means the "just give us more time" pattern of United earnings calls under former CEO Jeff Smisek may return.

Last week, Delta Air Lines Inc. (DAL) - Get Delta Air Lines, Inc. Report reported second-quarter earnings and issued current quarter guidance.

Delta had a slight miss on earnings. But it guided toward current quarter unit revenue growth of between 2.5% and 4.5%, operating margins of between 18% and 20%, and a capacity gain of 2%.

After the market closed on Tuesday, United reported second-quarter earnings and issued current quarter guidance.

United beat estimates by 3 cents. But it guided toward current quarter unit revenue growth of between minus 1% and up 1%, with a pretax margin between 12.5% and 14.5% and capacity growth of 4%.

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The guidance generally disappointed analysts. United shares closed Tuesday at 78.90. In premarket trading Wednesday, shares were down about 3%.

A report by Evercore ISI analyst Duane Pfennigwerth was headlined "Growth Hall Pass About to Expire."

"United's 3Q17 unit revenue outlook of flat y/y is below legacy peers, feels right down the middle of the fairway and likely portends down y/u unit revenue into 4Q17," Pfennigwerth wrote.

"While investors have been willing to overlook United's stepped-up capacity growth during a period of revenue outperformance, we wonder if the patience will continue," he said. He has an inline rating and an $83 price target.

JPMorgan analyst Jamie Baker wrote, "United 2Q earnings were broadly in-line with pre-released results {but} 3Q guidance appears to be a miss, from both a RASM and earnings perspective.

"We believe few were braced for a -1% to +1% outcome, which once again raises the specter of declining RASM," Baker wrote. He has an overweight rating and an $87 price target.

However, Buckingham Research analyst Dan McKenzie said that while the third quarter outlook is a "modest disappointment," he attributes it to a temporary "pricing disadvantage to AAL [American Airlines Inc.] and excessive domestic growth.

"We continue to like the stock 6-12 months out on pretax profit initiatives that should gain more given critical mass in 2018," McKenzie wrote. He has a buy on the shares and a $97 price target.

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