338 PA over many years is not a large sample size by any means. That is about half a season worth of PA spread out over 6+ seasons. That really isn't relevant because that could easily be explained by random variation.
If you read the column, you'd see that Boz offers more than simply regurgitating the triple slash line. Evidently his only real power is direct pull, or into Fenway's huge right field. Crawford rarely drives the ball hard to left of center. Also, Crawford's range as a fielder is going to be an underutilized tool in Fenway, per Boz:
Everything about Crawford's game is ill-suited to lopsided Fenway. His only flaw is a weak arm. In Boston's huge right field, he'd be a pigeon for the running game. So, he'll have to remain a left fielder. But he'll be stuck in the smallest left field in the sport, where the impact of his range is minimized and the hits he does manage to steal will mostly be singles, not doubles or triples.
Many elite lefty hitters blossom into batting champs in Boston if they have opposite-field power. You'd think that the 215-pound Crawford would fit the bill. And he may. But he hasn't yet. In his whole career, he only has seven opposite-field homers. And in Tropicana Field, only three of his 53 homers have been hit even one inch to the left of dead center field. On paper, you couldn't draw a hitter less helped by Fenway. Maybe he'll adjust.