Yes it is prooven that shooter games increase your reaction time significantly, not just cod, but shooters in general. I`ve seen some tests were players of the popular Counter Strike Source. Also the ones that played in clans with voice chat had increased their speed in speaking rate by 20~ percent. So from this i come to the conclusion of taht games increase performance were it is needed. SO you can easilly adapt to your daily routines, wich in this case would be fast reaction times and quickly inform others of what your position is and what observations you have. Also i have found it extremely, and i mean EXTREMELY annoying when people interrupt with what i do, especially when gaming. Probably because it demands very high level of concentration. So i think that playing games demanding full focus gives you more concentration skills, very good to help out when at school. Lots of irritation-causers there...
So summarize arch you belive in neuroplasticy?
(Because if you change your neural network you will gain knowledge and get a more efficiant neural network to accomplish more and more demanding tasks even quicker than before)
I suggest you try out lumosity, even though the games might seem even boring, its only three short games a day, obviously you could do these in the morning somewere, just to get done with your daily training. It also manages your routine so that you can pick what skills you want to improve on the most. Such as i picked memory and concentration as my first priorities, and then i get tests that helps me improve on those areas.