When it comes to the mechanics of your roping, it's all about angles. Because of the way a heel loop works, the angle of your swing becomes a very important factor. The most common characteristic of the angle of pro guys' swings is an angle that comes down over the left side of the steer on the left side of his horse's head.
Back to the mechanics of it, when you deliver a heel loop your main objective is to control the bottom of the loop as it comes through in the delivery process. You're wanting it to hit the ground and stay right in line with the bottom of the feet, or even come back toward you in the delivery. That makes it go right on the steer's feet as he's in the air.
When your swing has an angle where you're higher on the right and lower on the left, what that does is when you go to come out of your swing and into the delivery process, you have to pull it down because of that angle. That downward pull helps you bring the bottom of the loop down into your delivery, and helps make it stay where you put it.
One of the most common things that I see lower numbered ropers do is they'll start their swing in the correct position initially, having the tip pointed toward the steer coming down the arena, but then as their horse comes into the turn and everything squares up and lines up, their swing will level out over the steer's back and even drop lower than that level mark. They've got their elbow dropped down, and are now lower on the right and higher on the left, which is the opposite angle from what you're needing.
When you're lower on the right and higher on the left, you're swinging more on the right side of your horse than the left, and your elbow's kind of tucked down by your side. When you go to deliver the loop and your motion's going forward, when you deliver the bottom of the loop in place it'll go toward the front feet. You can't get the bottom of your loop to stay in place very well from that angle.
One thing I tell students at schools is when you study the tapes and are able to watch the good ropers, that's the first thing pertaining to the swing a person should realize. You need to understand that the good guys use an angle over the top, because that's the best angle to get your swing in if you want to control the bottom of your loop.
I personally swing with a lot steeper angle than most anybody out there. Some of the other pro guys, like Cory Petska and Cesar de la Cruz, also swing at a pretty severe angle over to the left. I don't suggest you get it that severe, but at least stay above the level line on the right side as it comes across to provide enough angle to get the bottom of your loop to stay in place on delivery.