I know almost every player has a 90%+ fielding %. It does not need to be mentioned. Also, scorer decisions are often arbitrary and just plain wrong. I hate using Flg% to judge anyone. It is near useless. Besides, a 5% difference is 1 error per 20 attempts. That's like turning a .290 hitter into a .240 one (or .330 if really good.)
Nobody is claiming defense is more important that batting or pitching, but really good pitching can turn sour when asked to make 4-5 outs in too many innings. And, when some team's get out of a jam with a skillfully turned DP, others let yet another batter come up. Even the best pitching is at a distinct disadvantage needing to get extra outs, too often.
I'm not one to blame any loss on one payer or one play, but there are easily 15-20 Red Sox losses that a bad defensive play or two led to the deciding amount of runs to score against us. Sure, better pitching could get us 15-20 more wins, too. More timely hitting, as well.
I'm not really worried about our defense, next year, unless Story is out again, and Rafaela is not in CF.