I agree with you on this.
Bucholz would be the number 5 pitcher, Gonzalez would be the number 4 hitter, and with more than 50 million coming off the books next year, retaining Beckett and V-Mart should not be an issue.
As stated above, the Sox have the money to retain Beckett, and they will, meanwhile, trading Buch for Gonzales and adding a league average number five arguably makes the Sox the best team in the Major Leagues.
Bucholz is good, but not elite, and the Sox have the possibility of signing Chapman, think about the short and long term benefits of securing an in-his-prime, elite-level first baseman.