It was the Ref that screwed this up. the Lions had used #70 several times during the game as an eligible player. You see this often on FG/XP. They were planning on muscle memory to kick in for the cowboys and they would just assume #70 was the eligible number, as he had been all game in various situations. You can clearly see that #68 made the motion to declare himself eligible and #70 did not. However, the muscle memory kicked in on the Ref and he announced #70 as eligible instead of #68. I do not know if the coaches can hear the announcement on the PA system at all, so they may not have heard the announcement. I have often seen a coach asking, which number was it, after a penalty because he didn't hear the Ref announce it. So its easy to see how they would not have known which number was announced. The problem is that the Ref only alerted the Defense in regards to #70, so 68 was not in the coverage scheme which is why he was open. It is hard to say if that screw up costed them anything. and they failed the next 2 attempts anyway. The nfl should just have players that have non-eligible numbers wear a pull over jersey in red or something and then there is no need to report or be announced.