The conspiracy theorist in me has this theory:
1. For the last two seasons, Mike M (and maybe analytics) told Jerry that Dak wasn’t the best at reading zone and has accuracy issues, and that the Cowboys might want to make an investment in a promising backup, but in the meantime, Mike would try and simplify the offense for him and install an offense that limits his weaknesses.
2. Jerry actually listened, and got Lance as a peace offering, but thought nothing more of it.
3. Fast forward to the end of the season, and Jerry starts to see it, and obviously can’t fire his head coach who tried to warn him.