2. The Baltimore Ravens do not trust their depth
The big issue here is both Jeremiah Moon and Tavius Robinson are not doing enough to fill the Ravens' concerns. If you watched the preseason, you saw that Tavius Robinson struggled throughout. He looked like it would take time to adjust to the NFL. Jeremiah Moon looked better than him. Even Malik Hamm looked better, but Hamm is on the IR as well.
With these two in, the run defense suffered. The Colts had 13 carries for 79 yards outside the tackles, per PFF. They were getting to the edges too easy. They had 17 carries for 43 yards when running at the big bodies such as Michael Pierce.
Moon can play the role of Bowser, who plays off of the football, but he is not the long-term answer here. If the Ravens do think Bowser will be out even longer, they have to sign Van Noy just to replace Moon. However, they also look better with Van Noy across from Jadeveon Clowney and then Tavius Robinson coming in as depth. Robinson is not ready to start right now, especially against a Browns rushing attack.