From JDS:

 

Tebow's gersey has the number  '15' on it.

In Hebrew, the number '15'  is actually  "yod-hey", "יה ", which is pronounced "YAH", the name of GOD.

So as to not announce constantly the unspeakable Holy name of God, the original number  '15', "yod-hey"  

was changed by the Rabbi's in modern times to "tet-vav", טו