Here's a great video by an ex-NFL QB breaking down Justin Herbert game film. Some of the best that's available publicly:
He said this will be the first of series of breakdowns he will do of the QBs of this draft.
What's funny is that TY was a late 3rd rounder, who was seen as a very limited WR. They basically said he was a "deep threat" only type of WR and didn't have the skills to be successful short to intermediate.
6.0 is simply a threshold I use to gauge the overall depth of WR. The ratings are directionally correct, but not the end all be all. The league is literally littered with high 6s that aren't WR1s, and sub 6s that are WR1s. Like TY, did you know Tyreek Hill was a 5th rounder. He was predicted to go undrafted... Last year was one of the better years for rookie production based on NFL.com's ratings, but half or more of the guys rated above 6.0 failed to attain 500 or more yards.
Did you know that Parris Cambell was tied for 2nd in last years grading (graded out at a 6.7), only behind AJ Brown? So if you're looking for a highly graded guy that has the ability to take over WR1, he has all the measurables and grading. I doubt the FO is giving up on his potential due to a bunch of unrelated (and some freak) injuries.
On that note, and assuming they aren't giving up on PC, CB and FR were both on record saying last year that they were starting him inside but had plans to gradually work him outside. That likely means Z (as he's not an X type WR), and probably means they viewed him as the eventual successor to TY. IMO, their intention might be to end up with PC at Z, and move TY in to slot to extend his career as he slows a bit. Then you also have Fountain that likely ends up in the Z/slot space (he might be able to handle speed/little X (but would not be a primary X IMO)
If the above is the case, that might signal that their biggest need is at traditional X, and if that's the case, there will be plenty 6.0+ to chose from in the middle rounds (Xs normally stay on the board longer). Check out the list of Xs and "guys that could project at any position" in the below thread. And even then, if they re-sign Funch (which they said they wanted to), that need might not be huge.
Could have. . . problem was that he continued his non-investment after it became clear that some of those guys where not going to work out.
Say Braden Smith didn't work out for some reason. By now Ballard is scouting day 1 and 2 OL in search of someone who will workout.
Hugh Thornton was drafted in 2013. 2 years later in 2015 it should be clear that Huge Thornton is not going to be a decent starter. Lets add that to the fact that at this point Grigs still doesn't have a decent center or right tackle (Cherilus had also busted by this point.) Only Castanzo who he inherited and Mewhort are actually working out to some extent. So you are still missing starters in 3 spots.
Grigson drafts Good in the 7th round and brings in no one else new on the OL.
2013. Grigson Drafts Bjorn Werner. Travis Frederick is still on the board.
2014 Grigson had traded for Trent Richardson - Joel Bitonio is still on the board
2014 Grigson drafts Donte Moncrief in the 3rd round. Trai Turner is still on the board
2015 Grigson drafts Phillip Doresett in the first. Donovan Smith and Ali Marpet are still on the board.
Some of those might have been considered reaches at the time, especially Marpet.
That was just a cursory search. Point was, he didn't make it a priority.
Let me be clear I'm not saying he IGNORED the OL (as in never ever tried). But he didn't make it a priority (as in fix this first than the rest.)
And when you have found yourself a franchise QB, keeping your franchise QB alive by giving him a functional line should be a priority.