There are any number of variables. One of the main ones could be that the descent was slow (ie the descent rate was not enough to give sufficient acceleration), or they might have reduced the thrust but via the autothrottles in an instance when it wouldn't be as apparant. Really there is no rule for this, just that an airspeed is usually needed to be maintained and thrust will just be adjusted accordingly. Though reducing thrust does improve economics for the airline.
I've seen it but can't remember anything about the descent. With my Sanford knowledge base I can tell you that if the descent was started around or before the BEENO intersection it may well have been quite a slow descent to landing as aircraft are at about 5000' by JESUP and by COZMO they'll have turned into final approach anyway (they used 27R if I remember correctly).
Hope this helps a bit.
SFly
[This message has been edited by SFly (edited 07 April 2001).]