I always find that there are far too many distractions at home!
I can be focused on exercise, but the phone rings and its for me, or someone needs a hand with something, a friend pops in, cricket comes on the TV, etc, etc!! And all of a sudden you have lost focus and workout has gone down the pan!
Whereas with a gym, once I'm there, the only distraction is the leggy blonde in the tight lycra outfit!!

So I will always work out a lot more focused and I can always ask a personal trainer to take me through a workout specific to a sport!
The only time I work out at home, is going for runs in Spring/Summer. I always think to myself that I will go for a run and then do some press ups, cruches, and other exercises when I have done my run. But once the run is over, I jusr stretch and jump in the shower. But at the gym I am happier to do some weights and all round exercises aftert the treadmill! Plsu the treadmill has a little bounce in it, so it's kinder to my knees!
The one advantage the home would have over the gym for me is no lycra clad women working out at the same time distracting me, although that wouldn't be a bad thing!