More bats coming to second team? That is right (8)

'more bats' is the definition.
(bats and screwy can both mean mad)

'coming to second team? that is right' is the wordplay.
'coming to' means one lot of letters go next to another.
'second' becomes 's' (common abbreviation).
'team?' becomes 'crew' (crew is a kind of team**).
'that is' becomes 'ie' ('i.e.' can be a synonym of 'that is').
'right' becomes 'r' (common abbreviation).
's' next to 'crew' is 'screw'.
'screw'+'ie'+'r'='SCREWIER'