Holt has seen Ruddy go from unwanted loan player at Everton three years ago, to a place in the England squad, although injury has interrupted his international ambitions.
"He has definitely got better and better," Holt told the Pink 'Un. "He had a massive disappointment this year when he did his thigh which hampered him for a long, long spell. That probably brought the wheels to a halt a little bit with the England thing, but he has come on leaps and bounds and it is no shock other clubs are interested in him.
"We know what kind of goalkeeper we have got there and I am sure that is why his name is getting mentioned with the so-called bigger clubs.
"The club will be desperate to keep him, we all want him to stay - we have a fantastic number one and number two as well in Mark Bunn, so the club is in a great position.