Mark Cuban says his Dallas Mavericks are still working on "developing our identity." In the meantime, he has a few interesting things to say about a certain tech giant.

"We've got to get that p--s and vinegar in us I think a little bit more," the Internet entrepreneur said on CBNC's "Fast Money" on Thursday, when his team was in second place in the NBA's Southwest Division.

While the billionaire entrepreneur and investor works to sort out his team's character, his thoughts on Google seem to indicate a similar struggle for identity as the Internet giant faces competition from an unlikely source.

According to Cuban, "right now, maybe Google's a short."

It wasn't a pretty week for Google shareholders. On Wednesday, market analytics firm StatCounter released a report saying that Google's share of the U.S. search market in December fell to its lowest monthly level since at least 2008.

That drop-off coincided with the start of Yahoo's partnership with Web browser Mozilla, according to the firm.

Then on Thursday, Stifel Nicolaus downgraded Google's stock to "hold" from "buy." In a research note, Stifel said: "We do not see significant sources of future upside for shares and believe the best days for shares may be behind it."

Cuban said that Google's core search business could be facing some serious challenges.

"Google is a great place to look for things that have been around for a while," he said, "but it's not a good place to look for what's happening now. That's part of the challenge it's facing."

Cuban's thesis focused less on the loss of search market share from Yahoo, and more on competition from an under-the-radar source: Twitter. "Google search doesn't have momentum right now. Twitter is actually a better search engine," he said.

Cuban said he uses Twitter "probably ten times more as a search engine" than Google.

"I'm more often looking for current things and current insights about what I'm doing now. So I think maybe things are changing for Google, and those are the types of things I look for when I make a trade."

RiskReversal.com's Dan Nathan, who is long Twitter, echoed similar concerns about Google's core strategy. He offered a plan for Google's hoard of cash.

"I think Google should buy these guys. [Google has] no social media strategy, they have no messaging strategy, and they lack a certain real-time search strategy right now," he said. "So to me, this kind of fits a lot of things that Google should be using their $65 billion in cash for."

"Fast Money" contributor and Metropolitan Capital President Karen Finerman said in a phone interview that Google is "still an incredible, formidable force in search." Finerman, who is a Google shareholder, added that Google still offers an attractive value proposition. "The valuation here is really quite extraordinary for a company in this position."

While Finerman agreed that buying Twitter might not be a bad idea for Google, she said the company's cash could also be put to use in other ways. "I do think they should use their cash to buy back stock. I would be very much in favor of that."