If you enjoy watching ball games, especially in person, the eye test is everything, and that especially applies to defense, which is the poetry of baseball. Home runs win ball games a whole lot more often than great defensive plays, but the latter are usually more exciting to watch.
I personally have strong memories of the brilliant defense Iglesias played in 2013. Whether keeping him was the best move or not for the team, I wanted him to stay to enjoy watching his glove, footwork, etc.
Instead, we have Bogaerts, who is a far cry from brilliant. And yet. He does bust his butt on defense, which he takes very seriously. He is also a much better hitter than Iglesias and this year one of our key guys in the lineup in a year when our offense is doing pretty darn good despite the weak bottom third of the order.
So I fall back on that dirty, rotten, stinking no good stat/approximation called WAR which says that over the past three years Iglesias has averaged 1.6 and Bogaerts 3.5 in the WAR department (pun intended).
And I remember something else. Iglesias started at SS for the Tigers in the 2013 ALCS when they played the Sox. He was brilliant, of course, but the Sox won that series, 4 games to 2, and they won it with a combination of solid pitching and timely (not not great--the Tigers had a good pitching staff that included Scherzer and Verlander) hitting. The announcers, as I recall, waxed rhapsodic over at least one and maybe more than one play Iglesias made. But that year Lester and Lackey were both excellent in the postseason, and the bullpen was first rate. The postseason team ERA in 2013 was 2.59 even though Peavy wasn't so hot. My point is that the defense was fine without Iglesias because the pitching was more than fine. And guess who played in 12 of the 16 games in that postseason with an OPS of .893? Xander Bogaerts, that's who. He had the third best OPS and the third most runs scored.