However, scans on his damaged left shoulder have now resulted in the 26-year-old going under the knife to repair the serious injury.
Fly half Crook also suffered a leg injury against Scarlets and will be out until early next year.
"Netani has had an operation on his shoulder on Monday which means he could now be out for three to four months - that is a significant blow for him and for us," said Ruddock.
"He has some damage around the shoulder joint and that has had to be repaired and stabilised. I understand the operation went very well and now it is a matter of rehabilitating him and getting strength back into the joint.
"George has got a stress fracture in his shin. That is why he went off against Scarlets and he will be out for a month or so while that settles down."
Ruddock revealed better news surrounding Kai Horstmann who has impressed in training this week and taken part in full contact sessions ahead of the Bath fixture.
"Kai is a great leader for us, he is very experienced in the Guinness Premiership and he is one of these guys that you know every week is going to do the right things at the right times," added Ruddock.
"He is someone who can help steer the ship with his leadership qualities and is someone the other guys look to.
"It will be difficult for him if he comes straight into the team and passes the fitness test, he will be coming in with no rugby under his belt.
"But he did that in pre-season against Northampton when he produced a man-of-the-match performance, culminating in a try. It will be great to get him back if that happens on Friday night."
Tickets for the big televised clash with Bath Rugby are still available from the Warriors Box Office and online.
Make sure you are part of the Friday night action - call 01905 454183 to book your place or visit the online Tickets section at www.warriors.co.uk