Is it just me or whenever a top team buy midtable players for the sole intention of added depth it almost never works out? We brought in Sidwell, Ben Haim, Pizzaro for the purpose of filling in when need be with no scope for more and come the end they weren't even trusted to do that. The only time it does work okay is when you buy a second choice keeper who knows his place.
In theory buying a second string Xl from midtable clubs should get you the required depth but it always tends to feel so unnatural when done that way. Strong depth tends to come naturally from either an academy player, a player you signed to make a starter but he didn't quite make that grade or a starter naturally dropping to that role when a superior player is signed (for example Welbeck once RVP was signed at United).