Assuming player fatigue exists in FB Mogul 22, the gamer should be able to specify substitution criteria to be used during games.

It does not appear to be done automatically by the AI since non-starting players rarely have any game stats (and these appear to be based upon formations or injury).

Can substitution criteria be added to the Team->Offense, Team->Defense, Team->Special Teams dialogs?

Suggestion 1 (easiest but an obvious kludge):
Add an input box above the Help button that displays the substitution setting for the player clicked on (and a second box that displays the value of return to play). Allow the value to be changed.

Suggestion 2 (a bit harder but not an obvious kludge):
Add input boxes (substitution and return to play levels) to the left of the position labels on the dialog box. Allow the values in these boxes to be changed.

Suggestion 3 (more work but cleaner and better from a user perspective):
Add a Substitution button between the Release and Help buttons on these dialogs (Offense, Defense, & Special Teams) to bring up a substitution dialog.

Clicking the button would bring up a dialog listing each player for the Offense, Defense or Special Teams (as appropriate).
The dialog would contain the player name, position, age, Overall and Peak ratings and Durability rating.
In front of the player's name would be an input box for the fatigue level at which he is to be replaced by a substitute (and a box for the fatigue level at which he is to return to play).

The reason for not setting a single substitution point for all players is that the quality of the substitute and durability of the player matters.
If I have a Running Back rated 88 and a backup rated 86, I might set the sub value at 92%.
However if the backup is rated 70, I would more likely set the sub value at 80%.
Durability could also factor into the sub value being set for each player.
There could also be a quick set box / button that would set all players to the same value.
With some extra work, the values displayed could be calculated by the AI based upon durability and the subs ratings. (perhaps a button to have the AI set the values?). This would be for those who want better than the same for everyone but don't want to do it themselves for each player - or for those who want an initial good guess that they can tweak.