What criteria can be used to determine if a company has a winning business strategy?

Whether the company is winning in the marketplace! whether its ahead of its competitors and growing

There are actually several strategies to building a winning business strategy:

Focusing on a niche market

Being a low-cost provider

Differentiation

Developing expertise or resource strengths in the industry

Determining if the business strategy is successful would depend on what strategy was implemented. The ability to increase market share and financial growth would be lag measure indicators that *something* was working, but that wouldn't necessarily indicate that the strategy is working.

One law which explains this is the law of unintended consequences. Consequences can be good or bad. A company could very well intend to differentiate itself, but inconsequentially capture a short-term "one-hit wonder", if you will.