Clynn a complete disaster? Outside of Dean Lovren who has been poor this season ( and also plays for a team that doesn't do defending well). Non of the others have been disasters. Clynn and Shaw have been injured. Clynn is actually a top fullback when he plays. Call Chambers was always backup material.Players who've looked good in defence for Southampton and got big moves and been a success: Toby Alderweireld
Players who've looked good in defence for Southampton and got big moves and been a complete disaster: Dejan Lovren, Jose Fonte, Luke "too fat for human clothes" Shaw, Nathaniel Clyne, Callum Chambers
Hard not to worry a bit about how much the Southampton system (which has stayed pretty similar since Poch, despite different managers) contributes to players looking good for them.
So your comparison is Alderwereld to Lovren. 1 good one bad... Ok