score:9
Outside of the Roman Catholic context, genuflection is simply kneeling or bowing to show respect. There's no right or wrong time to do this; the Bible doesn't say we must be on one knee before we take communion, nor that we must not genuflect at any other time.
In evangelical meetings, genuflection is sometimes used; sometimes as a result of an invitation to do so corporately, and sometimes spontaneously as individuals. You're likely to see the latter more frequently in more charismatic churches, where individuals are encouraged to express their worship in their own way, and to see the former more in more conservative churches, where there tends to be more direction from the front. But there's no real rule that I'm aware of in any of the main evangelical churches that says you must genuflect at some particular times. You're just as likely to see the raising of hands, or taking up of other postures, in exactly the same way.
I know little of Tebow - I prefer the kind of football where the foot and the ball actually make contact - but it would seem he is prone to kneeling occasionally, perhaps before a big kick or something; this kind of behaviour certainly isn't uncommon in sport (Jonny Wilkinson springs to mind). He might be praying, he might just be focussing his mind - we don't know for sure. We do know it's not necessary to be on one knee in order to pray, but we also know that such a motion may help to focus his mind and spirit on God (assuming he is praying) amid the noise and bustle of the football stadium.