At The Motley Fool, we poke plenty of fun at Wall Street analysts and their endless cycle of upgrades, downgrades, and "initiating coverage at neutral." While the pinstripe-and-wingtip crowd is entitled to its opinions, we've got some pretty sharp stock pickers down here on Main Street, too. (And we're not always impressed with how Wall Street does its job.)

Given that, perhaps we shouldn't be giving virtual ink to "news" of analyst upgrades and downgrades. And we wouldn't -- if that were all we were doing. Fortunately, in "This Just In," we don't simply tell you what the analysts said. We also show you whether they know what they're talking about. To help, we've enlisted Motley Fool CAPS, our tool for rating stocks and analysts alike. With CAPS, we track the long-term performance of Wall Street's best and brightest -- and its worst and sorriest, too.

No longer a sell
At long last, Nomura Securities has upgraded Boeing (NYSE: BA) from the dreaded sell rating. Nomura points to the stock's 9 percentage point underperformance of the S&P 500 over the past three months as proof of its previous wisdom in recommending investors reduce their exposure to the stock. But according to the analyst, Boeing's fall is now at an end. It's time for the stock to straighten up and fly right: "sales prospects of the new re-engined 737 and the start of 787 deliveries could see the company re-establish some momentum."

Indeed, just last week Boeing confirmed receipt of Federal Aviation Administration certification for its 787, and plans to make its first delivery of the bird to All Nippon Airways on Sept. 26. Reports say that Boeing has half-finished 787s stacked to the rafters these days, and has only been waiting for its cert-papers to begin deliveries to a line of customers stretching from AMR (NYSE: AMR) to Delta (NYSE: DAL) to United Continental (NYSE: UAL).

Moreover, this morning Boeing issued a press release trumpeting the popularity of its smaller plane as well. Equipped with new LEAP-1B engines designed by a General Electric (NYSE: GE) joint venture, Boeing says the new re-engined 737 will have "a 7 percent advantage over the competition." (A pointed jab at both Airbus, and the company that makes many of the engines for its A320neo, United Technologies (NYSE: UTX).) According to Boeing, the plane is already attracting strong support from five airlines that have made order commitments for 496 airplanes.

But do these news items alone suffice to justify buying Boeing?

Boeing: "Buy! Buy! Buy!" or just "Bye-Bye"?
After all, as I pointed out earlier this week, even Boeing admits that it's going to take "several hundred deliveries" before the company even begins to break even on its 787 program. Boeing has 827 orders in hand, of course, and more on the way -- but still, it's going to be awhile before this particular program starts paying off for investors.

By the same token, Boeing's boast of "496 order commitments" on the re-engined 737 may not be quite as good news as it sounds. These aren't necessarily 496 new orders after all, but just "commitments." (And the sad truth is that sometimes promises are made to be broken.) Switching emphasis, even if the orders are good, we're not even talking about 496 new orders here. While Boeing stated that it has five airlines lined up to buy the new plane, Bloomberg pointed out this morning that some 100 of the order commitments Boeing is so proud of come from one customer, AMR -- and that having already been announced, they're already included in Boeing's plane order count. In short, this is not new business, or even new news.

Foolish takeaway
Now, all this is not to say that Nomura is wrong to upgrade Boeing. As a matter of fact, I agree with the analyst that at 14 times earnings, with 12% five-year annualized earnings growth projected for it, and paying a 2.7% dividend yield, Boeing shares look enticing. But I still have concerns about how Boeing's free cash flow numbers continue to lag reported earnings -- the same earnings that create that low "14 P/E" I just mentioned.

Part of this problem, I suspect (and hope) stems from Boeing spending cash to build 787s that it's until now not delivered, and get paid for. Within a quarter or two, we should have a better picture of how much actual free cash flow Boeing is earning from its new 787 franchise. Until then, I'm with Nomura -- sitting on the sidelines, and looking for proof that the runway's clear for takeoff.