A left sided defender who is dominant in the air is entirely necessary IMO.
Spurs have just played the Asia cup game against Hull with Corluka and Huddlestone at centre back. Before the game pundit Peter Taylor was asked if this is how they would line up for the first league match. It would be OK against a lone striker, he said, but any Premiership side would put two up front immediately against this pair and they would be in big trouble. "You need a dominant presence in the air and it's Redknapp's major priority with Dawson, King & Woodgate all out for a while."
I think it was our major weakness last season too. It really hurt us.
None of Onuoha, Dunne, Kompany Toure or Richards can give us this dimension. These last two have good vertical spring but are not in the same class as, say Hangelaand, when we need to win aerial duels. The missing left side defender is also important, especially with Robinho or Petrov on that side. Barry will help a lot in this respect but what happens if he gets injured by another flying TBH dropkick. We're missing cover there because it's likely Johnson won't be ready for a while.
To summarise we want Lescott & Alonso or similar.
Now about full back cover......