Skipper King is widely regarded as one of the best defenders in Britain but has been bothered by a long-standing knee injury that severely restricts his training.
Somehow Tottenham and King have managed to get him on the pitch for games where he has performed as he usually does - well. Spurs without King are nowhere near as good as when he plays - and the similarities with Nelsen are strong. Neither are particularly pacy players but read the game well, almost intuitively, and (in spite of the fact that King gave away the penalty that cost Spurs their key match with Manchester City recently) have cool, calm heads, good techniques on the tackle, in the air and in distributing the ball.
Dawson has also had injury problems in recent times and Gallas will be 35 himself in August - no spring chicken. He is out for the rest of this season with a long-term injury.
Nelsen is a far more solid player than Sebastien Bassong, the Cameroonian player who shows more going forward than he does in sometimes scratchy defensive performances and who has now been shipped off to Wolverhampton Wanderers on loan. Kaboul has enjoyed a good season, far stronger than his previous performances for Spurs and has also been threatening at goal time lately.
But he too is prone to form and judgement lapses. So Redknapp's ploy in signing Nelsen looks sound - as long as that knee remains sound.
If Spurs experience more injury trouble at the back, at least they will have experience to call on in the race for the premiership and/or a Champions League place. It is probably not the time nor place to promote a youngster - or to depend on the likes of Bassong. Nelsen is a conscientious trainer and will keep himself fit and sharp - and the depth of feeling about his departure from Blackburn is probably evidence enough of the strong influence many fans felt he had at the club.
Redknapp has signed Nelsen only for the rest of the season with an option for another year - which means, in theory anyway, Nelsen could even see some Champions League action in 2013 or at least some extended premiership game time.
What that will do to All Whites' hopes of having him back for key matches in the build-up to the next World Cup is anybody's guess but it should not be forgotten that Nelsen was guarded with his New Zealand appearances when he first signed for Blackburn, preferring to cement his place there. It would not be too much of a surprise to see the same circumstances apply while he beds in at Tottenham.
So, to go back to that prediction at the top - Nelsen will play and do well for Spurs in the run-in for the premiership. It's a fair bet that King will go missing at some stage, that Kaboul will have a fall in form, leaving Dawson and Nelsen as the main centre backs. I'll go further.
There is a key match against Chelsea on March 24 - what price a Nelsen goal there or, perhaps more likely, in the match against his old club on April 28, just a few games away from the end of the season and likely highly important to Spurs' future. For now, we will have to wait and see if Nelsen plays any kind of role in Tuesday morning's match against Liverpool. He is in Spurs' rest-of-season squad of 25 and, if he is going to be any use to them, some sort of game time will surely be needed.
If Redknapp has showed good judgement in his signing of Nelsen, he may have erred in his tax evasion court case - where he has furiously denied lying. However, Redknapp admitted earlier to the jury that he lied to News of the World journalist Rob Beasley about how an initial payment of almost £100,000 came to be in his Monaco account.
When prosecuter John Black QC asked Redknapp why he had told the reporter the money was a bonus (contradicting former Portsmouth chairman Milan Mandaric's claim that it was an unrelated investment account) Redknapp said he wanted to get rid of him.
"I don't have to tell Mr Beasley the truth," said Redknapp. "I have to tell the police the truth, but not Mr Beasley. He's a News of the World reporter." He said he had decided to lie because he did not want to read a story on that money appearing in the paper on the day that Spurs were due to take on Manchester United in the 2009 League Cup final.
Now prosecutors have seized on that - saying that Redknapp told the truth in "an unguarded moment" to the reporter; that the money was a bonus and no tax was paid on it.
Lying to a reporter breaks no laws but it is a dubious practice which can mislead fans, sponsors and other stakeholders. As Redknapp discovered in court, it can also be used as a stick to beat you with.