Sunderland: Key detail in Jack Clarke, Ipswich Town transfer revealed | OneFootball

The star winger was let go for a seemingly small figure.

Sunderland will profit from any future sale of Jack Clarke, as part of a clause agreed in the deal that saw him join Ipswich Town, according to reports.

The reaction when the former Tottenham Hotspur winger returned to the Premier League for an initial fixed fee of £15 million, with up to £5 million in add-ons, as per Sky Sports, was a confused one.

It's a deal that reflects even better on Ipswich now that League One's Birmingham City have paid a similar price for Jay Stansfield, but that's more reflective of the Blues' financial power and willingness to spend than it is of the Tractor Boys' coup.

Businessman William Storey, who seemingly tried to buy Sunderland both before and after the takeover by current chairman Kyril Louis-Dreyfus, openly criticised the club's decision to sell Clarke, but one element of the deal that wasn't previously known has now been revealed.

Sunderland's Jack Clarke sell-on percentage

One of the reasons why people were so amazed at the fee that the Black Cats were willing to accept was because of the well-known fact that Spurs had a sell-on clause included in the agreement between them and the Wearsiders when he made the switch to the Stadium of Light.

The figure that they would receive from any future sale of the 23-year-old was reported to be 25%, meaning that Sunderland will have made not much more than eight figures from the initial fee that they received from Ipswich.

Now it has been revealed that Clarke's former club have their own sell-on clause now, which would see 15% of the money earned by Town from selling the winger down the road, according to the Sunderland Echo.

They also added that of the £5 million in add-ons that they could receive from Ipswich, £3 million is likely to be heading Sunderland's way in roughly the next year, and the other £2 million would come their way later down the road, but they are less likely to receive this portion of the add-ons.

The club's hierarchy were said to be very keen on including a sell-on clause of this nature in any deal so that they would also benefit in the future if he continued on the trajectory that he set for himself during his time in the northeast.

Clarke, who signed a five-year deal with Kieran McKenna's side and made his debut last weekend, started the new season well for the Black Cats, providing one goal and an assist in his two appearances. Former Spurs teammate Romaine Mundle has filled his shoes well though. He's found the back of the net twice since Clarke left.

Sunderland's model leaves them open to these types of deals

The way that Louis-Dreyfus and sporting director Kristjaan Speakman run the Black Cats has its ups and downs. They find gems like Clarke for a fraction of the price they end up being worth, make a huge profit on them and then use the money earned to fund further investment into the squad.

But, because they want the club to be ran in a self-sustainable way, it does mean that every now and again they may need to let go of a player like Clarke in order to improve the overall squad.

Speakman had said earlier in the summer that Sunderland were under no pressure to sell any of their prized possessions, but they obviously believed that this deal for Clarke was one that was worth doing.

Luckily for them, and thanks to their youthful recruitment model, they have someone like Mundle who can immediately pick up the reins that were put down by his predecessor and continue his good work.