The OL got pushed around at times by Clemson but every OL gets pushed around by Clemson. Next year 4 of 5 starters are back too so there should be some reason for optimism there.
The biggest problem was the vertical passing game which is two fold 1) Book was skittish from the start and 2) the lack of speed and athleticism at WR KILLED us. If Notre Dame goes into 2019 with the Boykin / Claypool / Finke trio starting, they will struggle with elite defenses again. Some combination of Austin, Keys, Lenzy, Young need to get in the mix if ND is going to move forward as an offense. Ideally I'd love to see Boykin / Young / Austin that's a trio with pure speed (Young), athleticism (Austin), and size (Boykin).