An outfield player touches the ball for a tiny fraction of a match. Scouting practice has always concentrated on the remainder, and event data has only recently begun to catch up.
On-ball actions are a thin sample
Even a central midfielder in a possession-dominant side spends only a few minutes in contact with the ball across ninety. Everything else is movement, positioning and communication.
Judging a player on that small window means judging him on a fraction of his contribution, weighted toward whatever his team's style produced.
A talented player in a side that rarely has the ball generates very little on-ball evidence at all.
Off-ball movement creates the opportunities
A pass exists because someone made themselves available, and the run that opened the line is invisible in the event record. Credit accrues to the passer.
Similarly, a defender who steps forward to close a passing option prevents an action that never appears anywhere in the data.
Prevention is systematically undercounted in football statistics, and off-ball work is mostly prevention.
Video allows the scout to ignore the ball
Broadcast footage follows the ball, which makes off-ball assessment difficult from a normal feed. Tactical camera angles showing most of the pitch are the standard tool instead.
Scouts watching a specific player will often track him for extended passages irrespective of where play is, which is only practical with wide-angle footage.
The availability of tactical feeds for lower divisions is now one of the main constraints on how deeply those markets can be scouted.
Tracking data made some of it measurable
Positional data records every player continuously, which in principle captures the off-ball work that event data misses. Measures of pressing intensity and defensive line coordination are built directly from it.
Interpretation remains difficult, because a player's positioning is largely determined by team instruction rather than by individual choice.
Separating what a player decided from what he was told to do is the central unsolved problem in off-ball evaluation.
Context is why the human scout survives
A scout watching live can see the coaching staff's instructions, the shape the team is holding and whether a player is compensating for a teammate.
That contextual reading is what turns a positional observation into an assessment of judgement rather than of obedience.
Clubs that have leaned hardest on data have generally kept scouts for exactly this reason, using models to decide who to watch rather than to replace the watching.