Good total GMAT score but low AWA

Hi All, I took the GMAT a month ago and got 750, but AWA was very low - 4.0 (20th percentile). I'm not a native speaker and I have engineering degree from an Ivy League college (very technical background). My goal is Top 5 US schools (e.g. HBS, Wharton, etc.) or a couple in Europe (i.e. LBS, INSEAD)...