user: Question: What was the manner of departure for the outgoing manager, Davide Ballardini?
Columns: ['Team', 'Outgoing manager', 'Manner of departure', 'Date of vacancy', 'Replaced by', 'Date of appointment']
Types: ['text', 'text', 'text', 'text', 'text', 'text']
Sample row: ['Siena', 'Mario Beretta', 'Contract expired', '27 May 2008', 'Marco Giampaolo', '27 May 2008']
SQL:

assistant: SELECT "Manner of departure" FROM "Table" WHERE "Outgoing manager" = 'Davide Ballardini';