This is one of the many reasons why Jace wouldn't dare try Quidditch; he was unaware of the happenings around him. Did he see Ace get yanked back and got fully dismounted from his broom? No. The Ravenclaw was too busy concentrating on the hoop before him, trying to fend off the thought that he'd trip his neck if he wasn't careful.

Concentration, precision...Jace was mentally taking down notes of his observations. If he were to master flying, he has to master the basics first. It was just like learning how to ride a bicycle. Once he gets the balance, and the general feel of riding it, then he'd be able to use a bicycle without aides.

After successfully passing through the first few hoops, Jace carefully manuevered the handle to the left to make a turn, and gently pulled up to ascend to the next level of hoops, following the fireflies.

No wonder Jakub liked this broom. It was precise, light to the touch, and very responsive. It looked like he's got a very valuable broom in his hands right now.