Marcos Alonso, younger brother of Xabi, has signed a 5-year deal with Chelsea. Alonso is the son of former Barcelona star Miguel Angel 'Periko' and brother of Tenerife midfielder Mikel. Both boys came through the ranks at Sociedad, with Xabi making his senior breakthrough in a Copa del Rey match versus Logrones in December 1999. Xabi and Mikel Alonso (LaLiga) La Liga Mikel and Xabi Alonso were born to play football and they were born to play for Real Sociedad , the same club their father Periko Alonso played for and coached. The Londoners paid around £23 million for the Fiorentina left-back, who …