He really wasn't even that bad against Indiana. His first interception I'm 90% sure the receiver ran a bad route, if you watch, the receiver cuts in like he's running a deep in and then suddenly cuts back up field. Second INT was bobbled around, not a great decision but came from trying to do to much. Ditto, the third, he was in the process of getting tackled and made a throw he had no business trying. Just a bad decision but again, not one that had anything to do with reading/processing defenses. Needs to just take the sack. He still threw for 300 yards.
Northwestern was a clunker though. Easily his worst game in college.
None of that justifies him falling. Again, people can overlook Trey Lance looking like a high school quarterback against nobodies in his one and only game and decide he's a top 3 pick? Talking about a guy with 4 200 yard passing games in his entire college career. If you watch anything beyond the highlights there is absolutely no comparison between Fields and Lance. Fields is an elite NFL prospect. He showed it time and again. Lance is a guy with little experience and less production against garbage competition.