He played well towards the end of last season and got a contract extension, so I don't think he is finished as a player. He did his cruciate 3 years ago and missed a bit of time with a metatarsal fracture too but he wouldn't seem to be a crock.
Apart from a groin strain has not been injured much this season, just not being picked by Koeman this season.
Matty James would be good but might take time to get up to speed after a serious injury.
Alan Judge would be in a similar boat if a move was made, out of contract in the summer but back in full training now.
Conor Hourihane would be worth the gamble too a he is also out of contract in the summer and can't be on huge wages at Barnsley.
Robbie Brady I like as a player but don't think he would be value for money.