This letter documents some problems in Ancaiani et al. (2015). Namely the evaluation of concordance, based on Cohen's kappa, reported by Ancaiani et al. was not computed on the whole random sample of 9,199 articles, but on a subset of 7,597 articles. The kappas relative to the whole random sample were in the range 0.07-0.15, indicating an unacceptable agreement between peer review and bibliometrics. The subset was obtained by non-random exclusion of all articles for which bibliometrics produced an uncertain classification; these raw data were not disclosed, so that concordance analysis is not reproducible. The VQR-weighted kappa for Area 13 reported by Ancaiani et al. is higher than that reported by Area 13 panel and confirmed by Bertocchi et al. (2015), a difference explained by the use, under the same name, of two different set of weights. Two values of kappa reported by Ancaiani et al. differ from the corresponding ones published in the official report. Results reported by Ancaiani et al. do not support a good concordance between peer review and bibliometrics. As a consequence, the use of both techniques introduced systematic distortions in the final results of the Italian research assessment exercise. The conclusion that it is possible to use both technique as interchangeable in a research assessment exercise appears to be unsound, by being based on a misinterpretation of the statistical significance of kappa values.