user: Question: Which Overall is the average one that has a Name of Vance Walker?
Columns: ['Round', 'Pick #', 'Overall', 'Name', 'Position', 'College']
Types: ['real', 'real', 'real', 'text', 'text', 'text']
Sample row: [1.0, 24.0, 24.0, 'Peria Jerry', 'Defensive Tackle', 'Mississippi']
SQL:

assistant: SELECT AVG("Overall") FROM "Table" WHERE "Name" = 'Vance Walker';