Paul Coll has time and space to take an unimpeded swing so although he is behind his opponent he is actually in a strong position within the rally
Yes the most important past of a length is to regain T position; you get your opponent behind you and you get behind them. It's quite difficult to apply pressure and attack from the back of the court, but this is changing and players at elite levels can pretty consistently apply pressure from any part of the court if they have 2 essential qualities, space and time.
A shortened swing played off the back leg forced by a good length by Joe Lee
So although it may sound simple and true that getting your opponent behind you is the main goal of length, but what exactly does a great length entail? Many people here say 2nd bounce in the back corner. This is generally true, but without any pace the ball could easily be taken before the ball gets to the back corner. So does this do enough to define what good length is? And furthermore is this a type of length you should be aiming for on every length you hit? Many will say yes, but I disagree.
Let's first get at how I define good length. A good length is a short hit to the back corners which simply makes your opponent adapt their normal swing. The more you can make them adapt their swing the better for you. Of course a major bonus is time pressure. If you hit your length with pace and you force your opponent to get to the back faster and try and play the ball off their back foot they will not be as accurate and will be forced to lift the ball, playing defensively.
So which is a more important quality of good length? Time pressure or the lack of space? You can certainly make excellent claims for either one. But we all know the player that hits really hard without any accuracy, so I don't time pressure is possible without some form of accuracy. This is why I like to tell the kids I work with that the goal of their length is to limit their opponents space in the back corners. The less space the player has to work with the more defensive they will be. Of course at a really elite level players can return a ball deep off of almost any length, but they are less likely to be able to reapply pressure when they have a very short swing, are choking up on their racquet and are getting super low to get under the ball. When I see my opponent doing any or all of these things I begin to move my T position not only over, but also forwards an extra foot or so and expect a loose ball to volley.
Coll in trouble due to lack of time and space!
When you begin playing you are unable to adapt your swing at all and hit a decent shot. This is why we see people resort to back wall boasts and the 2 handed shovel when they get stuck in the back. They are out of space and have no other options. As these players improve they will learn how to make the above noted changes to their swings to lift and get the ball back deep, but even for top players they won't be accurate or be able to hit with as much pace and they definitely won't be able to disguise their shot when they have this little of space to deal with. So if you want to improve your length and volley more think about trying to make your opponent shorten their swing and lift the ball from the back corners. Even if they have time it doesn't mean they will hit a good shot. If you play someone fast or has good hands this should also be your goal.
So although yes you need to get the ball by your opponent to get the ball to the corner, that in itself is not a sufficient definition for a good length in my books. Learning how to get the ball to die in the back corners is the tough part. As the ball gets bouncier this is even more challenging. If the ball is really warm you actually will want to take some pace off the ball, perhaps using a shorter punch type swing and/or aim to hit the sidewall with your length in the back part of the court so it takes additional pace off your shot. If your shot hits front wall, sidewall, floor and then back wall there won't be much energy left on the ball unless you've greatly overhit it. Learning to use some slice can also help take pace off the ball, but this can also make the ball pop out off the sidewall (on some courts more than others). Using slice and the sidewall to get your length to die in the back are tricks the old boys used a few decades ago when the game was much more attritional and it was difficult to shorten your swing and flick a length out of the back.
If you really want to help someone visualize their goal of a good straight length simply tape out a target for the second bounce on the sidewall, floor and back glass. Can you picture how this would make 3 sides of a cube and an excellent target for a good length? This also means that it is really important to learn how to dig ball out of the back and adapt your swing to get out of pressure. But it's tough to win by only absorbing pressure, you also need to be able to apply it.
I have to mention 1 last thing about good length. When I'm teaching someone the basis of the swing this is why it's important to learn how to have a compact swing and to swing forwards (and not backwards first) so you can get more balls out of the back corners with your regular swing without hitting the back glass. So the bigger your opponents swing is the easier it will be to pin them in the back corners.
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