Have they?
Nomar who's defense was on a serious decline used to be elite, but they traded him away for a defensive upgrade. Julio Lugo wasn't a bad fielding shortstop either and was considered a plus short stop, in 2013 they had Stephen Drew who was also a good short stop. Bogaerts was never a bad fielding short stop, he's just a gold glove caliber fielding short stop, maybe average.
I'd say the Sox like offensive-minded shorts stops who can at least be average on defense more than saying they don't like short stops who can't field.