The Midlands club have to be aware of when to cash in on players who can be replaced.
That is the view of sporting director Monchi, who worked hard to bring in new talent and balance the books this summer.
"If we want to be in the top we need to sell, 100 per cent," Monchi stated, per Birmingham Live.
"Because of our revenue - we cannot raise more revenue because of our stadium. We need to consider the profit as revenue.
"We need to consider in future that to sell a player is revenue. Because we cannot have more revenue. When Damian worked in Valencia and I worked in Sevilla it was OK to increase the level by selling players. The most important thing in my opinion is not selling players - the most important thing is to buy good (players).
"We were not afraid to sell players but we had to do it within a plan. In my opinion we need to sell players because City sell players, Arsenal sell players, Real Madrid and Barcelona sell players. We are not afraid to sell players - the most important thing is to have, one - a buyer, and two - buy a player to replace this one."