What you'd learn in a one-off dead rubber would necessarily be limited, but you'd get an indication of how they fit into the team environment (including making them feel part of it before they go away), how they cope against subcontinental bowlers, how they deal with the step up to a Test match with the bigger crowds, greater pressure, media focus etc, and get a view of how their technique stands up to the scrutiny of a Test quality attack.
I'm a sentimentalist and would prefer to see him bat, but can see why the argument to the contrary could hold sway in the selectors' room.
What you'd learn in a one-off dead rubber would necessarily be limited, but you'd get an indication of how they fit into the team environment (including making them feel part of it before they go away), how they cope against subcontinental bowlers, how they deal with the step up to a Test match with the bigger crowds, greater pressure, media focus etc, and get a view of how their technique stands up to the scrutiny of a Test quality attack.
I'm a sentimentalist and would prefer to see him bat, but can see why the argument to the contrary could hold sway in the selectors' room.