I'm assuming these are among the first you've tried in this area. Some excellent moments caught.
In this sort of photography I feel close cropping creates much more impact so in the first you'd crop out the legs on each side and the out of focus grass at the bottom. If for the media that's about all you could do due to paper's restrictions on having non-photoshopped images. If for yourself on the other hand or trying to sell, then you could clone out the legs behind/above them. It's a good shot as it is but I just feel the crop and clone would make it better.
With the second I quite like the background there - in this shot only - there's enough clarity to show the "ambience" or atmosphere, i.e. a typical grass roots rugby game. Great expressions too and a good story - he's nearly twice the size of the tacklers, will he burst through?
The third is the best shot and if you could zoom in a little (crop) and then spend a fair few minutes cloning out the post and rail, the leaf and then cover up the houses, that will be a cracking shot. The focusing is, as you say, slightly off but you can sharpening the scorer up in photoshop (or Lightroom) with a sharpening brush.
Re the focusing, I use the single spot in the centre for two reasons: first is to make sure I'm focusing on the subject I want and second on some cameras it is a quicker way (mechanically) for the camera to focus. Also (on Canons I don't know what it's called on other makes) AI Focus is good for this genre as the subject is moving towards/further away continually. And finally, a method called back button focusing will result in most photographs being in focus. With this you set one of your camera's buttons to focus and in practice when nearly taking a shot you hold this button down permanently and it will continually adjust the focus. Then press the shutter button and 99% of the time your subject will be in focus when the image is taken. Not using this button can lower the success rate very significantly.
Important bit now(!) - I've said all this to try and help - NOT to knock you for six!! I'm too frightened to play rugger, too old as well, but I do enjoy watching it and I like the set you've produced here. Good colours and clarity and plenty of enjoyable action.