However, he can call on international ace Talei and believe the big forward can make a real impact.
"The back row have played well so far this season, but Netani is a quality athlete and an international rugby player," said Ruddock.
"He is itching to get on the field and he showed up well when he came on against Wasps, carrying really strongly. He is an exceptional ball-carrier with the ability to break the line.
"He is a different type of player to Kai, who is a real general for us and a great 'old head' without actually being that old. Netani offers us something completely different in that he is not as much of a leader but is an exceptional ball-carrier.
"What we want to do is to get him making in-roads and running at opposition backs rather than just around the fringes at forwards.
"Netani will come in for Kai, but unfortunately James Collins has come down with a type of flu bug and didn't train on Monday or Tuesday so it is unlikely he'll make the squad. Matt Cox will probably come in on the bench."
Ruddock plans to pick from a similar panel this week but revealed that talented young fly half Joe Carlisle could come back into the mix.
He said: "With a bit of luck Joe will be back in contention to figure or be there or thereabouts in terms of making the bench.
"Shaun Ruwers should be back in contention at prop while Callum Black is back in the frame as he was last week so he has a sniff of trying to creep on to the bench as well."
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