...is the PF following the FD commands or is he chasing a pitch attitude?
HN 39:
If I interpret your graph correctly, your FD pitch bar plot represents the angular difference between the pitch attitude symbol (theta) and the FD bar, i.e. mostly within + or - a degree and one-half until around 72s.
If this is all referenced around your upper plot of a possibly active VS of +1500 displayed on the FMA, then you graph clearly shows that when aircraft vertical speed was below +1500 (48s-55s), the FD bar would be above the aircraft pitch symbol (theta), and vice versa when the aircraft VS was above +1500 (56s-67s), the pitch bar would be below the aircraft pitch symbol.
At 67s-72s the bottom began to fall out.
As to your actual question, since the trend for pitch is a generally consistent increase (not a specific attitude) with some minor variation (as would be expected control-wise with the speed decay) until the aircraft VS starts to go deeply negative, it sure looks like an attempt is being made to follow the FD until it can't be. I think as a practical matter the variations in SS input could be a result of the 'mushy' pitch response to the inputs as the stall is entered, as they are generally back and forth around neutral until the FD's are once again removed later. At which time the input is definitely only NU
indicating lack of cues requiring pitch 'fine tuning'.
I hope I stated this clearly, and it is of course just an opinion...there may be other explanations which fit.
However, I've observed a number of pilots making their first attempts at PRM (precision radar monitor) breakouts where the FD's are initially turned off, but can as a matter of course inadvertently return or be reselected in other than the desired mode, and the results can be spectacular both vertically and horizontally, and they're not even stalled.
(Question: Where did your FD pitch bar info come from? Surmised?)