Sales of the 2014 Chevy Silverado have been down in recent months. Photo credit: General Motors.

The numbers sure looked brutal for General Motors (NYSE: GM): While Chrysler's Ram pickups posted a 22% sales gain in January, and sales of Ford's (NYSE: F) F-Series were basically flat, sales of GM's Chevy Silverado dropped 18.4% on the month.

That followed a big decline in December. Chevy Silverado sales were down 16% in the last month of 2013, while Ford managed an 8.4% gain.

That sure looks terrible for GM, doesn't it?

It looks even more awful than you might think, because GM's pickups were all-new last year, while Ford's are an older model that is set to be replaced at the end of this year. If GM's new pickups can't compete with Ford's old ones, that's a problem, isn't it?

So here's the big question: Are GM's new Chevrolet Silverado and GMC Sierra pickups turning out to be busts?

Actually, GM isn't doing badly
It's easy to make that argument as long as you don't look too hard at the numbers. But the truth isn't that simple. To help us dig deeper into the numbers, I reached out to Edmunds.com senior analyst Jessica Caldwell, and Edmunds' big database of sales and pricing figures.

For starters, Caldwell pointed out that the Silverado 1500 had 17.4% of the light-truck market in January -- which is about what it had last March. These figures go up and down a bit over time as automakers change their incentives programs, but in her view, GM's share of pickup sales hasn't really changed much over the last couple of years. 

There's more evidence to suggest that GM's pickups are selling at a relatively brisk pace. "Days to turn" is an industry measure of how long (on average) a model sits on dealer lots before being sold. Days to turn for the Silverado in January were 78, versus 80 for Chrysler's Ram 1500 and 83 for Ford's F-150 -- and just 62 for the Sierra.

Caldwell also noted that GM's pickups have a larger percentage of "cash" buyers than the others, rather than buyers who are financed at the dealer or who choose to lease. That suggests that GM's buyers have relatively strong credit, and that they might be choosing more expensive, and more profitable, trucks.

That's consistent with what we've heard elsewhere. GM said in a statement early in February that half of its light-duty pickup sales in the fourth quarter sold for $40,000 or more. Those are seriously profitable pickup sales for GM, and a sign that its strategy -- pursuing more profitable sales, even at the expense of total sales numbers -- may be paying off.

So why do GM's sales look so bad?
So why the seeming ugliness in GM's sales numbers? Part of it is just a tough comparison: A year ago, GM had a big inventory of its last-generation Silverados and Sierras, and it needed to sell them off to make room for the all-new trucks that were set to roll out later in the year. 

That meant that GM's discounts were huge, and that drove up its sales numbers. Edmunds' data shows that GM's incentive spending per truck topped $6,000 on the Silverado 1500 last February, and was more than $5,000 in the first seven months of the year.

But that changed once GM's all-new trucks started arriving at dealers. Last month, incentives on the Silverado 1500 were down to $3,764 per truck -- lower than both Ford's ($3,925) and Chrysler's ($4,233). Incentives on the GMC Sierra -- a premium truck that tends to sell at higher average prices -- were even lower, at $3,521.

Long story short: GM's year-over-year sales are down in part because GM was running a big sale on its old trucks a year ago that boosted its total sales numbers.

I thought pickup buyers were loyal. Why do incentives matter?
Retail pickup buyers tend to be pretty brand loyal. A big discount from their preferred brand might get them to trade in sooner, but relatively few Ford buyers will trade in their old trucks on a new Chevy just to save a few hundred bucks, or vice versa.

Things are different when it comes to small fleet buyers, though. A contracting company looking for 10 new work trucks might care a lot more about price than about the brand name on the tailgate. For those buyers, incentives can make a big difference, and those kinds of buyers buy a lot of pickups.

As Caldwell pointed out, Ford's incentives on the F-150 started to rise just as GM's new pickups were arriving at dealers last summer. With a model at the end of its life cycle, Ford can afford to pay a little more per truck to keep sales strong -- it's still making plenty of profit on each sale. 

That has helped Ford's numbers look good.

GM is probably making a lot more money per truck, and more money overall
But GM's numbers don't necessarily look bad. GM's incentives are a lot lower than they were at this time last year, and its sales are a bit lower. Lower incentives mean more profits per truck sold.

But its percentage of the overall pickup market is in line with historical trends, and there's some good evidence that GM is making more profit per truck sold.

On balance, that sounds like a win for GM, not a failure. In fact, it sounds like GM's plan is working out pretty well.

The General's profit in North America was quite strong last quarter, at $1.88 billion. That came despite subdued-looking pickup sales. If that strength continues in the first quarter of 2014, I'll continue to be inclined to think that whatever GM is doing seems to be working.

How to invest in the next big thing -- explained by The Motley Fool
Let's face it, every investor wants to get in on revolutionary ideas before they hit it big. Like buying PC-maker Dell in the late 1980's, before the consumer computing boom. Or purchasing stock in e-commerce pioneer Amazon.com in late 1990's, when they were nothing more than an upstart online bookstore. The problem is, most investors don't understand the key to investing in hyper-growth markets. The real trick is to find a small-cap "pure-play", and then watch as it grows in EXPLOSIVE lock-step with it's industry. Our expert team of equity analysts has identified 1 stock that's poised to produce rocket-ship returns with the next $14.4 TRILLION industry. Click here to get the full story in this eye-opening report.

John Rosevear owns shares of Ford and General Motors. The Motley Fool recommends Ford and General Motors. The Motley Fool owns shares of Ford. Try any of our Foolish newsletter services free for 30 days. We Fools may not all hold the same opinions, but we all believe that considering a diverse range of insights makes us better investors. The Motley Fool has a disclosure policy.