The Tykes are looking to replenish their squad under new manager Michael Duff, having been relegated from the Championship into League One for the upcoming 2022-23 season.
And with Poland international Michal Helik likely to be cashed in on by the South Yorkshire outfit, new defenders are needed in the coming weeks.
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O’Brien has been a Palace player since 2021, having joined the Eagles from Cork City in his native Ireland.
A youth international for the Republic of Ireland at under-21 level, O’Brien’s only experience of senior football has come in the form of a loan spell in League Two at Swindon Town in the second half of the 2021-22 campaign.
At the Robins, O’Brien played 21 times, including in the play-off semi-finals against Port Vale, and standing at over six feet and five inches tall, the youngster would bring a considerable presence to the Barnsley back-line should they get a deal over the line.
With Duff favouring a back three when manager of Cheltenham Town, we can presume that it will be the same system that he brings to Oakwell with him.
Therefore, fresh faces are going to be needed at the back as there’s a chance that bids could come in for the aforementioned Helik, as well as Mads Andersen and Liam Kitching.
Despite his lack of experience in senior football, O’Brien is clearly on an upward trajectory, as evidenced when he slotted straight in to Swindon’s side from January onwards last season.
A move to League One is the next logical step in his development, and on paper, Barnsley would be a good fit.