If you're looking for a bullish view of the markets, BlackRock's (NYSE: BLK) Bob Doll is your man -- you can often find him on CNBC all pumped up about stocks. But it turns out that BlackRock may have been telling fund investors that the equity-market cheerleader was doing more for them than he actually was.

Doll is the chief equity strategist at BlackRock and the manager for the company's Large Cap Growth, Large Cap Core, and Large Cap Value funds. Or, at least, he is until he retires at the end of this month.

Ahead of Doll's retirement, though, BlackRock made it clear that Doll didn't do as much as was assumed in managing the Large Cap funds. As Reuters reported last week, BlackRock tweaked the language in the prospectus for its Large Cap funds, changing a line saying that it used a "proprietary multi-factor quantitative model" to reflect that it's using "quantitative factor models generated by third-party research firms."

It wouldn't be a terribly noteworthy change if not for one important fact: The models used by Doll were never proprietary.

This is an embarrassing oversight (it was an oversight, right?) for BlackRock to fess up to, but is it really that big of a deal? Probably not -- at least when it comes to individual investors. Most investors don't take the time to figure out how much they're paying in fees for the mutual funds they own, let alone read through the entire prospectus and take note of whether the manager is using proprietary or third-party models.

Not that this excuses BlackRock.

Flub or not, though, for my money, that's not even the most interesting line from that paragraph of the prospectus. This is: "A company's stock price relative to its earnings and book value, among other factors, is also examined -- if BlackRock believes that a company is overvalued, it will not be considered as an investment for any Fund."

This is a bold approach, but a smart one. Last I checked, the performance of Knucklehead Mutual Fund Company's Vastly Over-Valued Fund, which states "Knucklehead only considers investments that priced far above what they're logically worth," wasn't all that great.

Of course, the performance of BlackRock's Large Cap Growth Fund hasn't been so hot either -- and it has little to do with its "duh!" investment approach of avoiding overvalued stocks. The fund's current top holdings are Apple (Nasdaq: AAPL), ExxonMobil (NYSE: XOM), and IBM (NYSE: IBM) -- all of which I consider attractive investments. Yet the fund has fallen short of its benchmark in every non-institutional share class over the past one, five, and 10 years -- primarily because of the funds' huge fees. A-shares carry a hefty 5.25% front-end sales load and 1.27% in annual fees.

Interestingly, the top three holdings of Vanguard's S&P 500 ETF (NYSE: VOO) are -- you guessed it! -- Apple, Exxon, and IBM. And you can jump on that bandwagon for a mere 0.05% in annual fees.

Models may be the topic of the day for BlackRock and its Large Cap funds, but it's still fees, not models, that are killing mutual-fund investors.