Tottenham in general are a bit peculiar, and Defoe fits into the system of uncertainty there. Supposedly the season just passed was all about Gareth Bale, and to a point (Europe) it was, but, VDV and Modric were seemingly the most important attacking players Spurs utilised. But why was this? Both played in the advanced midfielder role, and were able to take advantage of space created by pace on the left (Bale), pace on the right (Lennon) and either pace upfront (Defoe) or more usually a target man to feed off when the ball was delivered from the flanks (Crouch). Proper defenders and wide midfielders prepared to work and track back denied Spurs this space and time and so their game plan was nullified.
And people at Goodison criticise Moyes for no plan B.
So far as Defoe goes, he requires the service Beckford still doesn't get, and is far less likely to get the headers Becks does as he is notably smaller and lighter.
We can all bang on about this striker and the next and the next after that, it wont make any difference until something significant changes in midfield.