The 26-year-old striker had scored 14 goals in all competitions since arriving at Harrison Park last summer, and insists he was happy to stay in the Moorlands.
But he decided to move on after Blues accepted undisclosed offers for him from Fylde, Airbus UK, Hinckley and Hyde.
McCarthy said: "I already knew a lot of the lads at Leek, having played with them for five or six years at Blue Mugge.
"But I didn't feel like I had the backing of the fans, and that was in the back of my mind when I made the decision to leave.
"There was nothing I could have done to please them, no matter how well I was playing. I was the scapegoat.
"I read the forums, I know a lot of people think me going is all about money, but I already make enough from my job. If anything, I'm on about the same as I was at Leek."
But McCarthy, an account executive for AXA Insurance in Bolton, hopes Fylde's cash will be enough to help reduce any financial strain on Leek. Town will also receive add-on payments if the former Blue Mugge captain, who has signed an 18-month contract, can help the Evo-Stik League Division One North leaders win promotion.
He said: "They always told me it wasn't a financial decision, but when they were accepting bids I wasn't sure whether they wanted me to stay.
"It's a good deal for them. They were worried I would leave for free in the summer, but I would have signed another contract.
"I know the club lost a lot of money when the Grantham match was called off, and the money they've received for me will certainly cover that and more.
"Hopefully it will mean no-one will have to take a pay cut."
McCarthy played under current Fylde manager Dave Challinor at Colwyn Bay last season before then Leek-director of football Neil Baker lured him to the Moorlands.
The striker had previously played for at least 13 other clubs, including Kidsgrove, Alsager Town and Chester, as well as having a trial at Crewe Alexandra.
McCarthy, who had not scored for Leek since November, said: "Neil was the reason I went there and to lose him (when he became assistant boss at Crewe) was a blow. I probably wasn't the easiest player to manage.
"But he is still there in the background offering advice to Lee Casswell, who is a top bloke.
"They've got a small squad and a lot of games to play, but hopefully they can still win promotion. I will be there to cheer them on if they reach the play-offs."