"He fell out of love with the game and hasn't played for two years but he came in at the start of July and met us and said he wanted to start playing again," Sky Sports News quotes Moore as saying.
"His attitude has been first class since he has been back and he certainly hasn't lost any of his ability. He has trained really well over the last month and has been getting fitter and fitter.
"When he's fully fit, I believe in Jason we will have one of the best players in League One."
The Welsh international started his career at Prenton Park in 1998 and had stints at West Bromwich Albion and Wigan, as well as two loan spells at Cardiff City.