I know him well, but I wouldn't say we were really close friends.
这里本是一般现在时,而but后却用了would ,were, 学生很是费解,期盼专家老师解惑。
这是一种委婉用法,请参见英语语法网的以下文章:
http://www.yygrammar.com/Article/200802/168.html