With the help of Pro Football Focus' play-by-play participation charts (which aren't 100 percent accurate and include some non-official plays, but are a good starting point), I think I've identified the 29 plays Ware missed last season. Other than a few last-play-of-the-game plays, I've confirmed most of them by looking at my game tapes.
Ware missed one play when he was shaken up in the first Commanders game (checked for concussion), three plays when he was shaken up against the Giants (stinger) and the last 13 defensive plays after hurting his knee against Seattle. That leaves 12 plays when he could have been on the field but was not. They are --
One play in Game 2 against Philadelphia -- With 3:39 left in the second quarter, Ware was replaced by Burnett in the dime defense. Ellis was already on the field and stayed on the field.
Five plays in Game 3 against Green Bay -- With a 27-9 lead and 3:43 left in the game, Ware was replaced by Hatcher for four plays in the dime defense. Ellis was already on the field and stayed on the field. On the last play of the game, Ware was replaced by Hatcher. Ellis was already on the field and stayed on the field.
One play in Game 5 against Cincinnati -- On the last play of the game, Ware was replaced by Spencer. Ellis was already on the field and stayed on the field.
Two plays in Game 11 against San Francisco -- On the third and fourth plays of the game, Ware was replaced by Spencer. Ellis was already on the field and stayed on the field.
Three plays in Game 14 against New York -- With 7:50 left in the third quarter, Ware came out for two plays and was replaced by Ellis on second and third downs. When the next possession started, they both were on the field. And on the last play of the game, Ware was replaced by Spencer. Ellis was already on the field and stayed on the field.
So when, exactly, could Ware possibly have been "hiding" from the coaches in order to get Ellis playing time?