IDK man. I watched every game last year, and several twice. TY simply isn't get a lot of separation (unless he's running in the seam). Compare the other WRs to TY. Here's all the pass catchers from 2020, and I included TY's from 2019 too.
TY20 - 1.26
TY19 - 1.5
PC20 - 2.11
MP20 - 1.58
ZP20 - 1.16
MJ20 - 1.64
DH20 - 1.4
JD20 - 1.2
MAC20 - 1.57
TB20 - 1.11
It looks pretty much like my eyes thought across the board. Looking at River's advanced stats,.... River's "on target" and "bad throw" %s weren't bad. Both Brady and Mahomes had higher bad throw %s than Rivers. Along with my eyes, there just really isn't a stat out there that supports placing the blame on Rivers (over TY).
Think about his QB the last two years, Brissett wouldn't throw until he saw them open which was usually to late allowing the CB to close separation and I remember throughout the season Hilton would make his cut be open but Rivers ball arriving late (due to it moving slow) to Hilton allowing the CB to recover and close the distance. I think we can all admit that Rivers and Hilton were never on the same page, and Rivers preference is bigger WRs who can grab a 50/50 ball which isn't Hilton's game.
I remember we had this separation talk before during the season, and I can't remember when do they measure separation? it's when the ball arrives to the WR right?
Edit: I got sidetracked as I was typing lol, anyways I think with Wentz's game/stronger arm fits better with Hilton, and he can potentially have a resurgent year