"When I came up here a lot of people at the club Wigan were saying to me they didn't think it was a good move. They were telling me it was a step backwards. But they were people who had no experience of what it is like at Ibrox and what a big club it is," McCulloch told the Sunday Herald.
"Most people haven't got a good word to say about the SPL down there. I don't know whether that is arrogance or whatever, but when we grind out these sort of results, it is good to shut a few people up."
After big results against Celtic and Barcelona last week, McCulloch added: "This is probably the hardest schedule that I've ever played under. I played in the Championship for a couple of years and I thought that was harder than the Premiership because of the number of games, but this is a different level again because you have got the number of games and they are against top quality opposition as well, so you have to look after your body."