The success of Rangers’ January transfer window activity is making a mockery of Celtic’s claims that there was no value to be found in the market, according to former Ibrox hitman Kris Boyd. In the end, only two players arrived at Parkhead between January 1 and February 1. And while one of those has been a big hit so far – Norwich City loanee Adam Idah scoring five goals in his first five Premiership games – the general consensus is that Celtic’s squad is weaker now than it was when the fireworks were lighting up the Hogmanay sky, especially after the Hoops shipped out Liel Abada, David Turnbu…