At this early stage in preparation for competition, Piper simply needs to do time working. Not hard work. And not overly stressful work. But he does need to put in his.... Mileage.
With Jeddien, my dressage partner of over 12 years, the last thing she needs is long haul mileage. Oh sure, like all horses, she needs a careful warmup of the muscles and suppling exercises. But after that, ring work involves reminders of what is expected of her. Her brain knows the work. Her muscles quickly remember the work. And even when she has had a month or two off, a good rider can climb on board, ask for, and get reasonable work from her without too much difficulty.
However, that is not the case with Piper. He does not have the experience, nor the miles of training that Jeddien has. He has not done thousands of transitions. He doesn't do 20, 15, and 10 metre circles in his sleep. He doesn't halt squarely and in balance out of sheer habit. And he does not yet know that he should be paying full attention to his rider until the segment of work is complete.
These are things that Piper, and all green dressage horses, have to learn as part of their dressage education towards competition.
For the rider, this is where patience and a good sense of humour comes in handy. Sure. When Piper is good, he can be wonderfully good. But, when he is acting like the less experienced green horse that he truly is... well.... it just makes one's eyes roll.
Lots of patience, lots of work, and lots of miles. It will all come together, in time. It always does.