Momentum investors love to back companies with the wind in their sails. Contrarian investors typically pick up the cigar butts the market has tossed aside. And what do you call investors who turn against winners? Sourpusses? Shorts?

On Motley Fool CAPS, we sometimes call them the savviest investors around. When one of our All-Star players -- those whose stock-picking prowess places them in at least the 80th percentile of our community -- sours on a top-rated stock, perhaps we should take notice. Perhaps the player has found a chink in that highflier's armor, or a question mark in its financial footnotes. Or maybe it's just a hunch. That's why these tables aren't lists of stocks to buy or sell -- just starting points for further research.

Here's a list of stocks that some All-Stars have recently spurned:

Company

CAPS Rating

1-Year Return

CAPS
All-Star

Player Rating

Vimpel Communications (NYSE: VIP)

*****

117.7%

jmt587

88.28

Cameco (NYSE: CCJ)

*****

(4.6%)

Jro81

99.47

Penn West Energy Trust  (NYSE: PWE)

*****

4.0%

TheSheet

98.94

Titanium Metals (NYSE: TIE)

*****

(33.5%)

ztrategist

99.50

ABX Holdings (Nasdaq: ABXA)

****

(60.4%)

rockingjude

90.02

Considering that, on average, 96% of CAPS investors who made a choice think that these companies will outperform the market, what might have turned some of CAPS' top players against these otherwise widely admired companies?

Go west, young man!
With oil prices reaching new highs, it has encouraged many companies to do more exploration, and Canadian driller Penn West is no exception. It's also been selectively acquiring interesting properties -- like its recently completed acquisitions of Canetic, Vault, and Titan -- and it finds the industry ripe for further pickings.

Natural gas, however, was a laggard in 2007, as prices didn't keep up with the torrid rise of oil. Coupled with a new royalty scheme in Canada, warm winter weather that has increased stockpiles of natural gas, a strong Canadian dollar, and volatility in the capital markets, Penn West found its stock falling by more than a third from its 52-week highs.

Yet gas pricing is improving steadily in 2008, and Penn West's stock has responded in kind, rising by 23% since the end of last month. While more than 600 CAPS investors think the oil and gas driller will outperform the market, a handful think there's the potential to underperform. CAPS player PMM2022 is a bear for the short term; he sees longer term upside:

High Natural Gas inventories are likely to drive prices down over the coming year unless there is a shock to the system -- either in terms of supply disruption or demand creation.

Longer term, however, there are reasons to believe the demand growth will pressure natural gas prices to the upside. This could come as utilities continue to install natural gas fired plants rather than coal in order to meet carbon dioxide emission limits.

Others, like JackCaps, think the new Canadian tax laws have created too much uncertainty. Penn West has acknowledged that it's also unsure how the tax laws will play out. 

Canada's proposed tax policy changes has created uncertainty for income trust companies like PWE. The 2007 Q3 10Q report describes provisions made for future taxes. None of this will help to increase the dividend.

While higher natural gas prices could certainly improve the company's immediate prospects, Penn West's position as a leading Canadian light-oil producer should give it the potential to make selective acquisitions, leading to consolidation that could improve its long-term prospects.

Make lemonade from lemons
We've seen the direction some of the All-Stars think these companies are headed, but Motley Fool CAPS is more than what the pros think, even if they're All-Stars. It's where we invite you to share your thoughts and insights. We're eagerly waiting!

ABX Holdings is a Motley Fool Hidden Gems recommendation. You'll end up loathing yourself if you don't take advantage of the 30-day, free trial offer available for any of the Fool's investment services.

Fool contributor Rich Duprey does not have a financial position in any stocks mentioned in this article. You can see his holdings here. The Motley Fool has a disclosure policy.