Middlesbrough should be looking to strengthen their attack this summer with Sammy Silvera expected to leave the club for Portsmouth. There has been plenty of transfer activity at Middlesbrough so far this summer, on the incomings and outgoings front. Behind the scenes, first-team coach Aaron Danks left the club to join German powerhouse Bayern Munich and was replaced by Graeme Carrick. Paddy McNair and Liam Roberts also left the club at the beginning of June when their contracts expired, while Hayden Coulson has recently joined Blackpool on a permanent basis. Now, reports this week suggest ano…