About MIT and IB

Today I was discussing the MIT admission process with a friend. He seemed to believe that MIT only wanted to see that he got 7s for predicted grades in his HL subjects, that MIT would only ask for the predicteds for HL subjects. Can anyone confirm/deny? Also, the predicted system feels pretty shaky to me, what if I have low 3rd year semester 1 transcript grades, but a high predicted? Semester 1 transcript puts my predicted IB at 35 (without the core 3 marks), while by semester 2 I would’ve dragged it up to a 39. Will this somehow cause doubt as to the validity of the predicteds? I don’t mind someone being honest, I would just like a honest opinion, preferably from someone who has the knowledge/mindset of an admissions officer.