I agree it does get busy at times.
I stayed in Cala Bona twice last year. At the Hotel Sur (opposite the Moreyo) in August and at the Moreyo in October. The Moreyo was busy in August - but that is true of most of the hotels in the area at that time. In October it was very quiet.
Talking to residents in the resort, I think the tourist season is becoming more condensed (maybe because of schools clamping down on kids holidaying in term-time)??
Dagnabit (hope I've got that right) is going in June - I think he should find it fairly quiet at that time. I'm hoping for it to be 'in-between' when I go in July as I am taking my teenage daughters and their friend with me.