Sunderland's sporting director says the exit of the likes of Jack Clarke and Ross Stewart - frustrating at the time for supporters when the [Black Cats](http://www.thenorthernecho.co.uk/sport/football/sunderland) were losing key figures - allowed the club to "keep building the squad".
[Sunderland's](https://www.thenorthernecho.co.uk/sport/football/sunderland/) healthy financial position enabled them to significantly strengthen this summer in preparation for their return to the Premier League, with the Black Cats spending in excess of £150m as they overhauled the squad.
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But several of the new recruits are young players who have signed long-term contracts, which gives Sunderland "security", says Speakman.
"You have to have conviction in your decision-making on these players," he said.
"The reason we have been in good shape with the Mayendas of this world, to be able to renegotiate, is because we've gone out really early and they're on five-year contracts. And some of the players that you've seen brought in, they're on long contracts. So we feel security.
"But we feel security because we've got conviction in their ability, their mentality, and their desire to keep improving.
"And we've tried in the squad to make sure that we've got some players that understand what tier one Premier League football looks like in Reinildo and Xhaka.
"Then we've tried to also have a blend of some younger players that we feel can play the level, which is super important, but also have the ability to have future potential and future growth.
"That's just sticking with our culture that we've always believed in since day one."
Sunderland won't be overhauling their squad every time a window rolls around, but club chiefs felt it was necessary in the summer.
"Moving to the Premier League is a reset on and off the pitch," said Speakman.
"You know, it's the best league in the world. It's the most competitive, fierce league in the world. And therefore, you've got to be ready to be able to compete in that. So it was important for us to be able to make the moves we've made.
"This is where our culture hopefully will come through, and it's the foundation of how we operate, which is we've signed a lot of players we believe that we can develop and coach and improve to be better. So with those players, if you're able to do that, you don't need to go out and sign another player, because Habib Diarra comes into the building and he grows with the club.
"We've always spoken about there's an end point. Naturally, you know, you see a lot of trades within the Premier League. You've seen a lot over the last few weeks.
"So that's always something that can happen. But for us, we want to try to grow the team. We certainly feel there's a number of players in our squad at the minute that can be part of the now and part of the future."
Trading has become increasingly inevitable for clubs in a PSR world, but Speakman believes Sunderland have shown it can be done smartly.
He said: "We've always tried to be consistent with what we're trying to do and how we're trying to do it. And we will always believe that those decisions and that way of working would put us in a positive position.
"The way you apply a new principle and maybe a new way of working, it takes time to be able to communicate that and for everyone to feel comfortable with it. We've always understood that and we've always understood that over that period of time we're going to take some critique on some of those decisions.
"But, you know, Jack Clarke, Ross Stewart, these types of trades that we've had have kept our transfers and our squad building going.
"And they're all really, really important. I think you can see that every club in the world is susceptible to trading and transfers and you have to be well prepared at the start with your contract and you have to be well prepared to be able to replace."