Marco Silva said Everton have taken a risk in not signing a central defender this summer and their portrayal as one of the Premier League’s big spenders is misguided.

Only Arsenal, Aston Villa and the two Manchester clubs invested more money in fresh talent during the transfer window than Everton, who signed seven players at a combined cost of £118.5m. Almost £80m was recouped in player sales, as Silva and the director of football, Marcel Brands, continued to clear out the deadwood left by their predecessors.

More than 20 players left Everton this summer and more will follow before the close of the European transfer window with Cenk Tosun, Oumar Niasse, Yannick Bolasie, Kevin Mirallas and Henry Onyekuru all surplus to requirements. Silva maintains Everton’s net spend is £28m rather than £38m, with the manager taking 10 loan fees into account, and the need to clear out so many unwanted players made for a difficult window.

Silva said: “It was a tough market for us. It is really tough now to buy a player – everyone is asking millions and millions and millions. But it was not just that. We have a big number of players under contract with us and Marcel and his staff, with my help, did a very good job to sell some players who were not part of our plans.

“I don’t know if many other clubs had 18 [senior] players leave like we did this summer but if they did it would be difficult for them too. I don’t like to speak about the numbers because it is not my role but just to be clear with everyone – and I know people are saying we spent this and this and this – we spent £28m in this window.”

The figure would have been higher had Chelsea been willing to sell Kurt Zouma or Crystal Palace, whom Everton visit on Saturday, been prepared to accept £60m for Wilfried Zaha. Palace’s stance ultimately prompted Silva’s move for Alex Iwobi, who is on holiday after playing for Nigeria in the Africa Cup of Nations and will not join his new club until next week, while the failure to land Zouma or an alternative leaves Everton extremely light in central defence.

Silva said: “First of all I have confidence in our three central defenders [Michael Keane, Yerry Mina and Mason Holgate] but it is not the best scenario for us. As I said, it was a tough market for us. We tried to reinforce that position because it was an important position from the first day. If you ask me if it is a risk then yes it is, but it is what it is and we have to manage the situation.”

Despite Everton’s defensive vulnerability Silva is satisfied with a window he believes has created “a younger and deeper squad with more quality”. He believes his track record of developing players is another reason to expect improvement this season.

“I am here to get our team better and to challenge for the big things in the Premier League and also the cups. If you look just at my time in England then who did Hull sell that summer? [Andy] Robertson and [Harry] Maguire. When I arrived there Maguire didn’t play at all. I can do this because it is the manager’s job to develop players. If they are the first, second or third target it is not important. They are our players. For me they are the best players in the world now and I am here to work with them. To get them better is my job.”