I remember all these matches played by Mou in da Chelsea, very instructive and Ive asked myself to have the option to have something like a bus defense... but IMO this would need a 2nd improvement, and would be a "formations training"...
Because we see many times managers doing 7 or 8 formation changes during the matches so... not real, and not so much logic really... I think that a bus formation "should have some advantage" as all formations, "if" are the main formations, so are trained having a better effect as in the real teams for example, we see every team playing with one formation or one idea under the field.....
Hope I explain the idea but basically for me train with a specific formation for the next match and use it, should have more stability.