global $wp_query;

switch ( $wp_query->current_post % 4 ) {
	case '0':
		$classes[] = 'team-first-column';
		break;

	case '1':
		$classes[] = 'team-second-column';
		break;

	case '2':
		$classes[] = 'team-third-column';
		break;

	case '3':
		$classes[] = 'team-fourth-column';
		break;
}