And Ruddock has admitted that both are now on course to make the opening day clash with Bath at The Rec on Saturday, September 15.
"I've been really pleased with the hard work that both Drew and Kai have done during the summer," he said.
"I'm confident that both of them will be in consideration for the first league game of the season and that is great news for us. I also hope they can have some real involvement in the pre-season fixture schedule."
New arrival Shaun Ruwers is also making good progress during the close season after going under the knife and Ruddock added that situation with giant lock Tim Collier was also encouraging.
"We've also been delighted with the progress of Tim since he underwent knee reconstruction," he added.
"His attitude has been first class and, while I don't wish to put any unnecessary pressure on him, he is currently ahead of schedule and is looking at a January return date at the moment."