You need both really. I sometimes find all the xA, xG, "successful take-ons" stuff annoying because it attempts to metricise football and it obviously doesn't quite work.
Also, the whole "record yards rushed" syndrome that afflicts the analysis of United States sports isn't really any good for football, which is a more fluent, complex, dramatic sport than any of grid iron, baseball or basketball due to the very highly variable length and patterns of the phases of play, the low number of goals, the high variation of results, the criticality of a handful of moments in a typical football match, and more.
However, at other times, people's rough descriptions of players or patterns are very much filled out or otherwise contradicted by the stats. I often find my own perceptions of a match are thwarted by the stats and that's usually helpful.
With Martinelli, I feel like what the stats don't quite tell you is that this is a player who we've seen in the past is a lethal and practical finisher. My thinking is that he's got at least double his current end product in him if he hits his ideal form and confidence.
