Grade your coach.
Triathlon training for Age Group athletes can be a complicated business so if you're after quicker improvement, hiring a coach could be the way to go. All sorts of factors impact our training and a coach who understands your life situation can help you improve your results quickly with a well thought out, appropriately structured training plan.
If you've been training for awhile and have aligned your ability to train with your performance goals, have faithfully followed your coach's advice and given his training plan time to take effect, and you've been honest about all factors that might affect your ability to train and race but you still aren't seeing improvement, it might be time to make take stock of the situation and see where you're at.
No one's perfect, so assuming your coach is going to make 10 out of 10 decisions right is not realistic. Instead, here's a simple grading scale a wise colleague once gave me for measuring your coach's ability:
A great coach will make 7 out of 10 decisions right -- and the athlete flourishes! Stick it out and don't fix what ain't broke.
A good coach will make 6 out of 10 decisions right - and the athlete improves. Keep at it with your coach and work on improving your routine if you begin to plateau.
An not-so-good coach will make 5 out of 10 decisions right - and the athlete stays the same. Ho hum, it might be time to have a good talk with your coach and refine your training regime, or move on to someone else.
A "bad" coach will make less than 5 out of 10 decisions right - and the athlete gets slower. Well -- this defeats the purpose of hiring a coach! Either the relationship's broken down or the training plans are poorly thought out for your situation. If you've both done all that is realistic to improve your performance and nothing's worked, consider that it might be time to move on.