The problem with Sinnott, as others have pointed out, is his snaps and production decreased as the season went on. Logan Paulsen questioned him some as well.
He needs to show enough that he finds ways to get himself on the field in ways other than special teams. Work his way into specific packages to start. We didn't see a lot of that.
McCaffery, I think was maybe taken a round or two early if the expectation is he was going to really produce right away. He made a position switch from QB to receiver, which is a hard shift, midway through college. He just had his first full off-season in the NFL. Now we can see where he is, and if he can work himself into some packages.
One thing his father said at the combine is they tried to have him learn all the WR positions all at the same time so they could see what stuck. That's probably good for the long term but not as good for the short term.
I still think the jury is out on both. Though I tend to be one of the ones where I give rookies A LOT of time. It used to be you judged a draft class after 3 years. I'm not sure it's that long anymore, but it's certainly after the second season.
I compare this to "regular jobs." When you get your first job out of college, you literally have no idea what you're doing probably for 3-4 years. It's all learning and development, with some hope of contribution. NFL, everything is accelerated because you only have elite graduates and it has to be because careers are generally over in your late 20's or early 30's.