Sunderland are set for the eighth summer transfer window since they were relegated from the Premier League. Sunderland fans won’t be looking forward to another summer of arrivals and exits, with a manager yet to be named and a number of their prize assets being targeted by Premier League clubs. Their long-awaited manager search, as well as a 16th place finish last season, could make bringing in quality players particularly difficult. Transfer signings have been on a gradual decline over the last year or so, despite Kristjaan Speakman showing plenty of promise at the start of his time on Wearsi…