Man... I got the +/- in my league match report. that means it is not only for scrimmages.
I´ve seen that in Spain, as other countries, it´s only available at scrimmages right now. Thinking of +/- is a Beta feature, we´ve to suppose that it´ll be available at all kind of matches for everybody soon but by now in some countries we´d have to wait.
Saludos.