Tapering off before Big Meet

I am at a loss on what to say about this tapering off before a big meet. I need your personal experiences to say whether or not it is a good thing for a swimmer. My daughter is currently on a swimming team in high school and did well with different coach. She shaved 30 seconds from the beginning to her last meet within one month and a half period. She excelled at each meet after she attended regular sessions of : 3X morning workouts in pool/dryland exericise (one hour and 15 minutes) and 4X afternoon workouts depending on how many meets she goes to (if there is a meet then there is a 3X afternoon workouts and a meet). Finally, her coaches told her that there is a tapering off which is no more morning workouts and fewer afternoon workouts for about 2 weeks. My daughter was not too happy about this but she followed through. Finally, she did not swim at all as per her coaches' orders for four days. When she went to her Big Meet, she did not even meet or exceed her previous personal bests. My daughter was devastated by this that she did not want to be consoled by us. My husband and I really wonder if she did not need tapering off but a simple two days off. My husband and I notice for ourselves that we'd be at least a few seconds faster than the week before after two days off of rowing. We'd be full of energy and roaring to go - we do not need tapering off to help us achieve our best. Our daughter did meet her best or exceed after regular workouts but not tapering off. The coaches might know something that we don't know. I want to have documents in front of me (BTW, one of the swimmer's mother threw a fit after her daughter gained 8 seconds in her 500 and gave the coach a hard time - our team has always been the joke around here - hopefully, our youth team will help make a difference with new and better coach). Does tapering off help or hurt your performance?