Milroe played poorly and the 2 INTs completely changed the game and let Texas play from the lead.
Milroe has no pocket presence and moved himself INTO sacks.
His INTs rightfully made Rees very nervous, so they had to run the ball on nearly every first down after those. Texas knew it, loaded the box and attacked the LOS. That made it impossible on the OL to block everyone and for the RBs to find holes.
The difference in the game was QB play and an OC who could call pass plays whenever he wanted and be confident, and another who had to call plays to minimize the risk of yet another INT or sack.