Sure you can. It's simple, has Cabrera saved move runs with his glove than Nomar would have contributed with his bat?
Without conclusions let, here are a few numbers. Batting average on balls in play, that is, batting average with strikeouts removed. The Red Sox allowed their opponents to hit .315 before the All-Star Break, compared to .313 in August. Meanwhile, their K:BB ratio, a defense independant stat, has risen from 2.28 to 4.2. A 4.20 K:BB ratio. The next best in August was 2.82, from the Minnesota Twins Now, judging from those stats, is Boston's recent upsurge the result more of the improved fielding, or the improved pitching?