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: Great news for Oshkosh (NYSE: OSK) shareholders! Your company beat earnings by the proverbial penny this morning. Unfortunately, it also warned that it's unlikely to repeat the feat, and as a result, its shares now sit alongside the likes of OfficeMax and Skechers -- among the worst performers on the NYSE for today. While the damage isn't as bad as earlier this morning, shares are still down 9%.

So what: Why the tumble? There are a couple of reasons here. First off, even if Oshkosh "beat estimates," its results were nothing to crow about. Profits of $0.74 per share were a bare fraction of what Oshkosh earned a year ago. Pentagon spending cuts are beginning to bite, and management says revenues from its defense business will come in about 5% to 9% lower than previously predicted.

Now what: Worse, the company's civilian lines of business are not yet picking up the slack. Crimped municipal budgets are strangling purchases of Oshkosh's emergency vehicles and garbage trucks. Combined with weaker defense spending, Oshkosh's revenues are down 39% versus last year's first quarter. That said, analysts still expect Oshkosh to earn $3.78 per share this year. They say it will gradually ratchet that number up over time, eventually accelerating to give the stock a 13% long-term growth rate. At just six times earnings, now might be a good time to buck the herd mentality and buy Oshkosh when everyone else is most frantic to get rid of it.

Is Rich right? Could Oshkosh really be a bargain? Add it to your Watchlist and find out.

Fool contributor Rich Smith does not own shares of Oshkosh, but the Fool does. The Motley Fool has a disclosure policy. Fools may not all hold the same opinions, but we all believe that considering a diverse range of insights makes us better investors.