Beattie was a serial goalscorer in his six and a half years as a Saint, finding the net 76 times in 233 appearances, and worked closely with Adams as first-team coach at Birmingham City.
“He's still quite raw, but technically he's improving all the time," he told the club's website. “He's powerful, fast and he knows where the net is.
“He's 23 years old, but in the 15 months we were working together, he probably matured about eight years!
“His biggest improvement has been in his mentality and his approach to his football. I think he takes it more seriously now and he understands what he could be.
“He's still a little bit shy. He's not an outgoing sort of person – he will be within the group, but maybe not with everybody around the club.
“He's a good lad – a nice kid – and he's going to do well if he carries on in the same vein that he's showed over the last 15 months.
“He's a good player. I don't really like the word 'potential', but he's got all the attributes to become a folk hero here."