If you have a bad/new healer specially in the lower ranks you are bound to lose.

[ThirdChild_ZKI]

But at around platinum new healers should stop queing for XP and start doing it on a job they play the best, or their rating will stagnate.

As a general rule, don't queue Ranked Feast for XP. Unranked 8v8 and now 4v4 exist to help facilitate this now, as well as allow a means of live practice.