In sharp contrast to the team that performed superbly at the back in 2022-23, the Magpies have conceded 54 goals from 33 games during 2023-24.
As a result, Eddie Howe's side are in a fight to secure European football for next season, the club currently sitting in seventh position in the Premier League standings.
Although Newcastle will naturally be making plans for the transfer market, which reopens in June, their spending power will be influenced by whether they are able to add continental action to their schedule.
The North-East outfit have already been restricted in that area in January, needing to ensure that they continue to meet the Premier League's Profit and Sustainability regulations.
Diomande on Newcastle's radar?
Nevertheless, it appears that Newcastle are prepared to show ambition in the next transfer window, particularly when it comes to strengthening their defensive options.
According to A Bola, Newcastle are now regarded as the frontrunners to sign Diomande in the summer ahead of the likes of Arsenal, Liverpool and Chelsea.
The report suggests that the club's hierarchy have already been proactive in attempting to determine whether they can afford the player by holding discussions with Sporting.
Diomande is said to have a release clause of €80m (£68.53m) in his contract, although it remains to be seen whether any club meeting that fee is realistic.
A total of 23 appearances have been made by the Ivory Coast international in Primeira Liga this campaign, Sporting well on course to win the title ahead of Benfica.
Sporting have incredibly won 26 of their 30 fixtures, yet their defensive record is marginally inferior to their nearest challengers and Porto.
Is a transfer to St James' Park realistic?
Howe will be prioritising a new centre-back in the summer courtesy of Sven Botman and Jamaal Lascelles both sidelined in the long term with knee injuries.
That has left Howe feeling the need to switch to a back three to accommodate Fabian Schar, Emil Krafth and Dan Burn, Newcastle having more wide players to rely on to feature at wing-back.
As it stands, though, that does not look like a long-term solution. Schar, Kraft and Burn are 32, 29 and 31 respectively, with Krafth having been rarely used over the past year due to a long-term injury.
Newcastle may have to cash in one of their star men in order for a move for Diomande to be successful, yet it may be deemed value for money with the player only 20 years of age.