Earlier quoted context omitted.
Having worked with AQR, I would say they are more HF + coupled with some tend following than anything else. What makes you say they are not?
To be clear, when you say AQR is primarily a "high frequency" firm, do you mean they are mostly position neutral with execution in (at most) a few microseconds?
This is how the SEC characterizes HFT firms.
1. Use of extraordinarily high speed and sophisticated programs for generating, routing, and executing orders.
2. Use of co-location services and individual data feeds offered by exchanges and others to minimize network and other latencies.
3. Very short time-frames for establishing and liquidating positions.
4. Submission of numerous orders that are cancelled shortly after submission.
5. Ending the trading day in as close to a flat position as possible (that is, not carrying significant, unhedged positions overnight).
From pages 4-5 https://www.sec.gov/marketstructure/research/hft_lit_review_...