Neither Timani nor Horwill are mobile enough to be blindsides in my book. They are mobile tighthead locks. Horwill in particular, the guy gets through a mountain of tight work - watch him closely sometime, it's incredible the way he gets around the park for a guy of his size. And saying that, he's not a six, not even close.
Those first two games in 2011 I thought that backrow of the Reds with Horwill at 6, Quirk at 7 and Higgers at 8 one game and Houston at 8 another (I think) was badly found out. The two teams that found them out were the Force, with an incredible backrow and average tight 5, and the Tahs, with a fantastic and balanced pack (before the injuries started, and correct me if I am wrong but they didn't field a real openside either that game - edit: oops, it was Phil Waugh, but I'll leave it up to you to decide if he was a fetcher by that part of his career).
Guys who can play lock and blindside tend to only be passable at one, and they end up being generally a lock playing blindside, or blindside playing lock, instead, of, well, a lock at lock or blindside at blindside. They'll shine in an odd game, but games where the hammer comes down and you need a specialist in that position you'll come up short. Horwill in those games looked very much to be a lock playing blindside.
I am another that believes the backrow is about balance. You need players that complement each other's strenghts and weaknesses, and the strengths and weaknesses of the tight 5. If you play Timani out wide, for example, then playing Palu out wide and picking Higgers makes no sense. Picking Hooper and Pocock you need three other good jumpers, two on them very good. Not to mention that short lifters do have a large effect on the height reached by the jumper.
On Timani, I personally wouldn't carry him when you want three good jumpers, particularly if the other lock is Douglas or Horwill, neither or which is terrific in the air. I'd take Horwill and Douglas as the locks currently myself, they jump a lot better than Timani (who seems to have issues with his spring off the ground) and should be able to lift (which can be an underrated skill) just as well. If you are carrying Timani just to be a big munter in the middle of the park then your pack is unbalanced elsewhere.
Again, picking Pocock and Hooper will work for a faster, open game. A slower, grinding game with lots of set pieces on a heavy pitch will be the undoing of it when faced with a massive pack who are aiming to belt the crap out of you.
Without the right balance, with the wrong conditions and/or up against the wrong team makeup and you will be toast.