There is a line you will pass between 200 and 300mm in my opinion.
In my opinion, the shot you posted here seems very adequate in telling the story with the other players, the playing field and some back ground included. If you zoomed in tighter with a longer lens then the entire frame would be filled with just the player your focus would be on and those other elements would not be included.
If you want a lens that will take in the entire field from one end, then an even longer lens like a 400mm would be the way to go. But if you want to be willing to work at positioning yourself for the shot then the 200mm is adequate for Rugby.
The main reason I went with the 300mm lens was for that extra distance that wild life is usually found that I couldn't reach with the 200mm lens.