In this contribution we focus on measures for characterizing array designs in terms of beamformer performance. The specific beamformer considered here is the MVDR beamformer. We first combine two existing performance criteria into an informative measure that qualifies both noise reduction as well as beamformer robustness to uncorrelated noise. Based on the results obtained with the new measure and on simulations of linear array configurations, we introduce the distance histogram as an instructive tool to qualitatively rate an array for beamforming performance. The aim throughout is to generate optimal microphone positioning with wideband audio signal applications in mind.