Why does it have to be either/or ? How could it hurt to have a number of guys who can fill multiple roles >
Again, it's not a question of whether Tebow would be "better" at any one of those positions. That's the thing about "all around" guys. Yes, you can find someone better individually at position W, or X, or Y, or Z. But you then have to factor in the value of the versatility as well as the value of the additional roster spots. Teams generally don't expect TE4, WR7 or RB5 to make huge contributions or dominate games. These positions are "bit" roles, largely to be there in case of injury or to give guys higher on the depth charts a breather now and then.
An underlying precept to my argument is that Bill and company see some value in carrying Tebow on the roster as the #3 QB. Whether that means that they are hoping that they can groom Tebow to replace Brady down the road, thereby allowing them to trade Mallet for picks. Or, perhaps they think that Tebow might only develop into a decent #2, which would still allow them to trade Mallet and draft Brady's successor at a later date. Or they can get Tebow to show enough in preseason games (this year or next) to trade him for a fairly high draft pick.
In my view, any of those would be enough reason to carry Tebow as the #3. BUT, if you add to it the fact that he could fill the roles of TE4, WR7 and RB5, that provides much more value than that provided by either Develin or Harrison. This is without even factoring in them possibly using Tebow to run the scout team for practicing to stop zone/read or mobile, scrambling, difficult to bring down QBs.
Yep. Should definitely make for interesting times.
TL;DR version. IF Belichick sees value in carrying Tebow as #3QB anyways, i.e. he'll definitely be on the roster, it makes sense to try and use him at other positions as well. Thereby freeing up additional roster spots.