Learning to differentiate model distributions from observed data is a fundamental problem in statistics and machine learning, and high-dimensional data remains a challenging setting for such problems. Metrics that quantify the disparity in probability distributions, such as the Stein discrepancy, play an important role in high-dimensional statistical testing. This paper presents a method based on neural network Stein critics to distinguish between data sampled from an unknown probability distribution and a nominal model distribution with a novel staging of the weight of regularization. The benefit of using staged L2 regularization in training such critics is demonstrated on evaluating generative models of image data.