Bemused by some of the talk here guys... Firstly, yes Lawes is a big hitter and good defender. But if we're talking of stopping the fatties on the gain-line Haskell is your man. Regardless what you think of him as a player and irrespective of the sin-binning, I'd still have him over Lawes at 6 10 times out of 10. I can't see why you wouldn't go for a blindside at blindside, and instead choose a lock(versatile? Meh..) at blindside.
Regarding Vunipola, I think his presence in the squad might be giving a misleading impression about how close he is to breaking into a match 23. I would have said he's there to learn and pick up experience. I still don't think he's there yet. I still remember seasons stats for both Waldrom and Vunipola whch were compared at the Leicester Wasps game.
#1 Vunipola: wins on Metres, offloads, defenders beaten
#2 Waldrom: win on Turnovers won, Missed tackles(as in, the least), penalties conceded
It seems to me that the coaching team we have would select Option #2 10 times out of 10.