It seems as if the majority of successful football clubs have tended to possess a solid core of homegrown/local players. I am thinking of teams like contemporary FC Barcelona (which usually start at least 8 Spaniards and Catalans + Messi, who is homegrown), Manchester United (quite a few influential players from the academy, many British stars), FC Porto (won the 2003 edition of the Champions League with 11 Portuguese nationals in the starting line-up), etc. To what extent is the lack of a significant "local backbone" (implying that more than 60% of the players are foreign-based, like in the cases of FC Arsenal or FC Inter, to take two examples) a hindrance for sustained success (success attained over the course of more than one season) in club football? Is the importance of "player spirit" (the willingness to fight tooth and nail for the team representing one's city or one's local community, as exemplified by characters like Jamie Carragher and Gary Neville) overrated or underrated?