This is a completely backwards idea.
Why take someone away from their area of specialist knowledge to learn CPR all over again every month?
What is a "chest tube", by the way?
Did I say CPR, I can do CPR, most people can get a pretty decent amount of help done based on what they've seen on TV, its the simplist thing there is, bar calling 999.
A doctor any time anywhere might be called on to help in an emergency, being practiced at a procedure is the difference between screwing it up and not. A rusty doctor might do more damage than no doctor at all.
What if in an emergency they need a doc down in the ER to help out because of a mass casualty situation what use will they be if they can't remember how to safely do simple things.
Also its a case of seeing other problems, the classic thing people say is show an x-ray to different doctors with a "blob" on the chest, an oncologist see's cancer, a cardiologist see's an enlarged heart, a ortho see's a broken bone, etc, etc, etc.
People make incorrect diagnosis constantly in hospitals because they don't think outside the box. A cancer specialist see's cancer patients all the time so won't easily recognise TB or some other problem. The best doctors are those that have a broad base of knowledge and don't limit their diagnosis based on the name of the department on the door.
A GP, trained and experienced 20 years before, a patient comes in and while there they have trouble breathing, they can't intubate because they've forgotten how even though they've been trained to do so, just not done it in 30 years. If he worked twice a month in an ER he'd probably be able to do it then and there, practiced and smooth as anything.
A specialist , lets say an oncologist, won't be a worse doctor for spending 2 days in a month in another department, they'll be BETTER, and 2 days won't make them worse in their own specialty either. Their are serious benefits and no downsides.
It also means, if you float an ER guy up to work in the oncology department, they get more familiar with how cancer presents in hard cases, that means a guy coming in with back pain might instead of being sent home with an ibuprofen, that same guy, because of the 2 days he did up in oncology, might catch that guys cancer early enough to save his life.
Rounded doctors are the BEST doctors.
End of the day, footballers are part of a multi-billion pound a year industry and the economics of that industry defines what is justifiable as a cost and what isn't. If you are disheartened that you work your ass off for nothing, then move to a market where your skills are in higher demand. I bet if you had the skills to be part of a leading premiership team, you wouldn't be complaining. 
but then again, I'd much rather be a doctor than any kind of sportsman, I'd like to think if I could do both to a high level, I'd much prefer being a doctor. personally feels a more worthy cause, but as i've said, not a sportsfan, so i'm biased 
