Although we don't believe in timing the market or panicking over market movements, we do like to keep an eye on big changes -- just in case they're material to our investing thesis.

What: Today was one of those blue moon days for Joy Global (NYSE:JOY) investors when the stock climbed 5% after the mining equipment maker improved its financial year 2014 profit guidance, albeit marginally. But for a company that's been battling the mining industry slowdown for a couple of years now, even a flicker of hope is big hope for investors.

So what: Joy Global's first-quarter revenue slid 27% year over year, in line with analyst estimates. But its net profit plunged 65%, missing Street estimates by a gaping margin. The most worrisome part of the report was the 16% drop in bookings, indicating how weak the end markets still are. The good news was that after dropping consistently, and by a staggering 42% during financial year 2013, Joy's Q1 backlog was sequentially flat. Since backlog serves as a pointer for a company's future potential revenue, it looks like Joy Global's top line may have finally found a bottom.

Now what: Joy reiterated its 2014 financial year revenue guidance range of $3.6 billion-$3.8 billion, but raised the lower end of its projected adjusted earnings range by $0.10 to $3.10 and $3.50 per share. Now I can hardly call that an upgrade.

But if you still want to see some good in it, you should also know that, given the drop in new bookings, the tiny improvement that Joy expects to see on its earnings is based on lower costs and not improving sales. Margins can be improved through cutting costs only to a limited extent. Even if Joy hits the higher end of its full-year projection, it will have ended with 24% and 40% lower year-over-year revenue and earnings, respectively.

That said, while today's earnings report didn't have anything in it to justify the jump in Joy Global shares, the worst may be over for the mining-equipment company; and most of the pessimism may have already been baked into its share price. I'd still remain on the sidelines, but not expect the shares to fall much further.

This article represents the opinion of the writer, who may disagree with the “official” recommendation position of a Motley Fool premium advisory service. We’re motley! Questioning an investing thesis -- even one of our own -- helps us all think critically about investing and make decisions that help us become smarter, happier, and richer.