פירוש על ברכות 57:7

There is confusion between Johanan, i.e. John Hyrcanus, and Jannaeus (=Jonathan, see Derenbourg, op. cit. p. 95 n.), i.e. Alexander Jannaeus. The former was at first favourably disposed towards the Pharisees, but in the latter part of his life opposed them (Schurer, i.i. pp. 288f.) ; but the latter was throughout his reign hostile to them and massacred numbers of them ; ibid. pp. 300 ff.

In holding that Johanan and Jannaeus were identical, he assumes that he had been originally wicked and that accounts for his later lapse.

If Johanan was originally righteous, how could he have become a Sadducee ?