Dallas Cowboys 13 at Baltimore Ravens 24
Third-and-2, Dallas at BAL 10, 4:20 of Q3
Dallas substitutes a number of players into its short-yardage package, while the play clock runs. While Dallas is getting set, four or five Ravens substitutes run onto the field. A few seconds later, two more Ravens sub out while three Ravens sub in, so at that point the Ravens have made two waves of substitutions. Despite the play clock running and Dallas already in its formation, for some reason the referee is standing over the ball, preventing the offense from snapping. By the time the ball is ready for play, the play clock has been reduced to under five seconds, and the Cowboys (to avoid a delay of game) signal time out. A Ravens player (James Ihedigbo) attempts to signal a time out, despite Ed Reed's protestations. Ihedigbo is not a captain, and therefore his signal is ignored. Dallas is charged with a timeout.
The inimitable Mike Carey, after the TV timeout, announced that "we were late spotting the ball, so that took the timeout away." Dallas received its timeout back, which was absolutely correct, because they called the timeout to avoid a potential delay of game due to the officials' error. What confuses me more is why Carey was guarding the ball until the second wave of Ravens defenders left the field.
Rule 5-2-10 allows a defense to substitute after an offensive substitution:
If a substitution is made by the offense, the offense shall not be permitted to snap the ball until the defense has been permitted to respond with its substitutions. While in the process of a substitution (or simulated substitution), the offense is prohibited from rushing quickly to the line of scrimmage and snapping the ball in an obvious attempt to cause a defensive foul (i.e., too many men on the field).
Baltimore has a right to make a substitution in response to Dallas' substitution. There was a slight mechanics breakdown by the crew (the umpire is supposed to guard the ball from entering play and wait for the signal from the referee), but I'm not sure it had anything to do with what happened. The issue is Baltimore's second wave of substitutes. Once the substitutions were made, the rest is at Baltimore's peril. Carey should have moved off the ball and allowed the play to proceed, since Baltimore had a chance to substitute and merely did so ineptly.
If Carey really had believed the second wave to be part of Baltimore's substitution by right, then his options were to reset the play clock (what Tony Romo wanted) or call an officials' time out (what Jason Garrett wanted). Hamstringing the Cowboys by guarding the ball during action that most likely would have resulted in an illegal substitution, then forcing a timeout (even if reinstated) was the worst of both worlds.