tizlinda,
A horse's response to the pace of the race is the defining aspect of a horse race. Either it sets the pace (runs 1st) or it overcomes the pace-setter(s): only ways to win.
So, for example - a horse may ran 'evenly' against a fast PoR in its last race (let's say F1 and F2 or the race through the 2nd Call point) and finished evenly but out of the money, perhaps in the top half of the field. Or, it may have faded due to the 2nd call energy expenditure being too much for their inherent ability, or too much that day (i.e. for that stage of their form cycle fitness), and they may have stopped running or faded badly.
In either event, the last line can look bad both positionally and by beaten lengths. But - if you switch the Velocity view to PoR (you can also watch the Adjusted screen or check the raw splits on Original, but Velocity equalizes distances and applied ITV and DTV adjustments - so apples to apples) you may see an even effort against a PoR faster than anyone else has faced, or faster than the expected pace setter today will set or can withstand. That bad or mediocre last line is now revealed as a potential hidden effort.
Checking the Pace of Race Velocity, or Adjusted times or Raw times can show you that, and not only for the last line, but any line. Visualize what PoR has the horse faced in the past, and what were its running positions versus various velocities - thus what can it face and what can it not face (its 'comfort zone' as Rich put it). Or, notice improvement/decline, e.g. by a younger horse or by an older horse returning from a layoff: against successively faster PoR, is it improving its position (and/or beaten lengths); against the same PoR or slower, is it not improving its position or falling back, over the last few races.
Try identifying the fastest PoR in all horses' last race (aka FPLR - check 2nd call velocity and True Speed, TS) for the E and EP positional runners and you will get an idea what likely pace today horses will be asked to face, and thus whether horses who faced far faster recently or in their past will appear to 'wake up' today.
If anyone has some specific examples of this, some screenshots or more links like David's would be instructive. (There's dozens each racing day...
)
Ted