In 2017, six rookie quarterbacks started at least one game in the NFL. Most of them had a rather rough season to start off their NFL careers. Each guy is in a different situation and that plays a part in whether they fail or succeed.
Trubisky was the second overall pick in the draft after the Bears moved up one spot to take him. After the first four games of Mike Glennon playing like he was mistakenly paid $45 million, the Bears moved on to the future of their franchise. Trubisky didn't play great but he wasn't necessarily bad either.