Putting product in charge of engineering instead of making is a partnership. Then not holding product accountable for an inspired roadmap that is delivered 2 m

Putting product in charge of engineering instead of making is a partnership. Then not holding product accountable for an inspired roadmap that is delivered 2 months into the half. My team is working way below peak efficiency for 4 months a year as a result. The engineers are super unhappy about this but there is "nothing to be done" according to my boss and his bosses boss.