The FDR shows a good demonstration of an increasing performance shear, albeit quite small. The autopilot is pitching below the horizon, the flight path is ballooning, the airspeed is increasing, and the ground speed eventually begins to decrease. Of course the auto-throttles were probably reducing thrust too. Automation is not always your friend. Click, click, maintain attitude and slope, accept the airspeed excursion. Non-event.
The power lever angle and AOA traces would also be informative.