Stock prices in the U.S. energy sector are already showing pressure into 2015, and there could be more bad news to come when several key players report their fourth-quarter results next week.

The group has been falling alongside crude oil prices, which are down about 60 percent since June. That drop has led to not only weaker shares but also sharply lower earnings estimates for both the current quarter and the full year.

Some analysts see long-term strength in the sector, and energy names are among the most undervalued in the S&P 500 (SPY) according to StarMine's measurement of intrinsic value, which looks at anticipated growth over the next decade.

In the near-term, however, many analysts feel the earnings revisions have not been severe enough, and that the bar, while lower, is still too high for companies to clear. Further disappointments could lead to continued weakness in the group.

Energy company earnings are seen tumbling 25 percent in the fourth quarter, according to Thomson Reuters data, a bigger decline than the drop of 19.8 percent forecast at the start of the year. For the full year, earnings are seen down almost 45 percent, nearly twice the decline of 23.3 percent forecast on Jan. 1.

Nick Sargen, chief economist at Fort Washington Investment Advisors in Cincinnati, said it was common for earnings worries to be assuaged as companies beat the lowered expectations, "but this time, we're getting validation of those worries."