One bad season in the Championship (his first full season at senior level) doesn't make him a bad player - and seems a stupid time to sell. His value is on a dip.
Look at Lukas Nmecha. His first season on loan he got 4 goals in 44 appearances compared to Delap's 4 in 37.
Then he had an even worse second season splitting his time between Wolfsburg and Middlesbrough scoring 0 in 25.
Finally he had a loan at Anderlecht - a much easier team for him to fit into stylistically and he we was soo good Wolfsburg, who he had flopped at on loan, came back in for him for decent money.
I say give Delap a loan somewhere like the Belgian league, Eredivisie or SPL and watch him score goals and then make our money on him.