The move to Stags’ arch-rivals has provoked a mixed response from fans.
But Radford today said: “The last offer from Chesterfield, which concluded the deal for Sam’s transfer yesterday, was good business for the club.
“Sam made it clear that he wanted to move and was unlikely to accept a new contract with us when his deal was up at the end of the season, and the club would have effectively ended up with nothing.
“Upon greater reflection at the weekend, and in the best interests of the club, it was therefore right to sell Sam at this point.
“We have a solid, tight-knit squad here at the Stags, now boosted by the signing of striker Rakish Bingham.
“Our club is still developing and growing after three progressive seasons.
“Sometimes really tough decisions have to be made, not always popular ones either. But those decisions are always made with the best interests of Mansfield Town Football Club in mind.”