The Celtic fans are expecting big things from the club in this summer’s transfer window. Not least because of the vast sums of money sitting in the bank account but also because, from day one, Brendan Rodgers has always said he wants to improve Celtic’s standing on the European stage. But to do that costs money and Celtic have been urged all season to splash the cash to help them at least compete with teams in the Champions League. But spending vast sums of money, whilst improving your chances in Europe, doesn’t always guarantee that a player will be a success. Just look at Vasilis Barkas and …