for an immediate promotion but narrowly missed out on the Championship play-offs in 2013–14 and Adkins and Crosby were sacked in December 2014. On 2 June 2015, Crosby joined Adkins as his assistant at Sheffield United. Adkins was sacked in May 2016 after overseeing an 11th-place finish in League One during the 2015–16 season. On 7 December 2017, Crosby was appointed as Adkins' assistant at Hull City on an 18-month contract. During this 18-month period Hull would avoid relegation out of the Championship at the end of the 2017–18 season and then finish 13th in the 2018–19 season. In June 2019, Adkins announced that he would be leaving Hull City, together with Crosby. Crosby said that they had decided not to renew their contracts as the wage bill had been cut and the playing squad was in need of a rebuild. He began working as Ian Baraclough's assistant in the Northern Ireland U21 coaching set-up, before being appointed as caretaker-manager after Baraclough was promoted to the senior team management position in August 2020. Baraclough described him as "a safe pair of hands". Crosby named his squad at the end of August and took charge for the remaining five group games of the 2021 UEFA European Under-21 Championship qualification. He won his first game as a manager on 4 September, a 2–0 win over Malta, and said that "it's a great opportunity for me as this is a really good group and Ian has put together a really good culture". However a 1–0 defeat to Denmark at the Ballymena Showgrounds on 8 September ended the team's chances of qualification. The rest of the campaign saw a defeat at home to Finland and a home win and away loss to Ukraine. Northern Ireland finished fifth in the group and it was reported in January 2021 that Crosby was expected to be given the manager's job on a permanent basis. In March 2021, he joined the coaching staff at Port Vale until the end of the season. He extended his contract at Vale Park in June 2021, at which point both manager Darrell Clarke and director of football David Flitcroft emphasised his importance to the club. He stepped down from his management position at Northern Ireland in order to concentrate fully on his role at Vale Park. On 15 February 2022, Clarke took a period of leave after a close family bereavement, with