Ok, Thanks for that.
How long has the season got to go? Can he take 3 weeks off?
Theraband is going to do nothing considering the amount of forces he is putting his ankle thru in 90mins of football (and i think you mean soccer right). I would do the eccentric loading exercises now and back his training off and teach him how to strap himself for game day.
Another alternative if taping helps is to use a small orthotic for his boots. You could probably get away with a "ladies" slimtech soft interpod orthotic as they go well in soccer boots. They are small, narrow and flexible to be in those shoes yet supportive enough for this purpose.
An alternative for treatment might be just to see him on a "strapping" treatment where he only comes in for 5 mins but pays half price. You can run 5 mins late for your next patient but get the extra income...The ground rules would have to be established that he is only there for strapping and a full appointment is required for advice, treatment etc. If he doesn't like the fees, he can learn himself when he pays you for a full session.
The eccentric exercise is outlined in Clinical Sports Medicine but essentially it is the lateral edge of the foot over the edge of the step. The eccentrically lower the foot into eversion. Then return to position - can use other foot to take the load off on the return so exercise is eccentric only.
See how you go with that!