They have contain, the sooner they make that happen, the less time to develope blocking downfield.
Theres three D linemen and two ILBs, and the opposing line can get a hat and seal the inside backer given time.
If the D linemen dont let the opposing O line get into them with technique and speed and strength, they can steer their way into any gap, and thats not happening enough.
If those D linemen hold their ground, the OLB steps in and turns the play inside, the ILB should be able to make the play.
It starts up front,if the D linemen are holding their ground,theres no obvious cutback lane,the ILBs arent caught up in the wash,and can move into the gap following the rbs moves.
Making the play is still having a free hand to pinch even tighter any holes,which gives a smaller target for your ILB.
The ILBs still have to hit the right angle, just a smaller one, because the OLB turned the play inside early, the D lineman is effectively affecting two gaps, as the ILB follows the rbs motion.
Being too slow lets the O linemen get into them, get leverage,and they can do two things, one, get their head on the play side of the D lineman, and then seal or push the D lineman wider or back,causing the wash to make a chase instead of an angle for the ILB.