I think that Dawson Knox can be a TE1, but I'm not opposed to adding to this position.
Tyler Kroft getting injured early was bad for him, and when he came back, he didn't do much.
Tommy Sweeney has good potential, but is not likely a starter in this league.
Lee Smith is primarily a blocker, and Jason Croom is completely outclassed by this group.
Adding another TE via free agency would be great, the idea of having Austin Hooper on the team is tantalizing, but I doubt that the Bills are going to approach free agency that way. I think they may be content to go with who they have and address other needs.
Drafting a Tight End is possible, but they may wait until Day 3 to do that.
Knox & Sweeney are the foundation to build on. I like Kroft, but the injury issue is a big problem, and I would be fine if he was cut from the team.
Lee Smith has been frustrating with a few costly penalties this season and he doesn't add much to the offense. However, McDermott loves his team leaders, and Smith is good at that. I would not be shocked if Smith sticks around because of that.