 Charles Rosen, for example, has the view that the essential feature of the piano concerto is the contrast between the solo, accompanied, and tutti sections; and this psychological drama would have been ruined if the piano was effectively playing the whole time, albeit discreetly.In support of his case, Rosen argued that the published figured bass of No.13 (K. 415) was error-strewn and thus not by Mozart; that Mozart's realisation of the figuration in No.