Rich, I can understand your desire for your daughter to do well, but she is 15. There is no need to get caught up in the bush league antics that permeate high school track and field.
I realize it is difficult for parents to separate themselves from the kind of BS that occurs when adults pollute kids athletics, but there is no “weakness” to speak of. The guy is a loser, and he’s trying to play mind games with you. Ignore him, he is a bush league coach and has exposed himself as such with his pathetic interaction with you.
We have discussed this before- I think the only weakness is an unwillingness to focus on competing against herself for the time being, and forget about the competitors in her races. Lowering her 100 and 200 metre time is important for improving future performances at all distances, not worrying where she places in races at 400 and 800 metres NOW- junior races that frankly don’t matter at all. You are the coach, and I think your guidance toward a longer term approach is needed here.
As a case in point, my athlete has raced seven times this year, and has set six personal bests. He is focused, motivated, and thrilled with his results- and hasn’t won a SINGLE race. I think you should encourage here to leave “running to win / place / show” to the professionals competing for a prize purse, and focus on improving her speed, especially since you know the track programs in your area will not do this during the high school season.