I am assuming that you saying Ferguson will be there at 90 is because your reference for this, which is reading media sites, has consistently listed Ferguson as a third round-ish option. But these sites do not encompass the opinions of any of the teams, and it only takes one team to draft him to make that not true.
For the Rams specifically, which to my eye is a big slot weapon who can plug in right away and body defenders while Stafford feeds him to move the chains... Not every TE is a fit. Some of these guys are gonna be more inline types. The ones who have pass game threat and polish tend to go off the board by round 2.
The Rams board for filling that specific role I would imagine goes something like Warren > Loveland > Arroyo > Taylor > Ferguson > Fannin > Gadsden. After Gadsden you're operating on hopes and dreams of guys with some tools developing things they have not yet consistently put up on film. I haven't watched every TE in this draft, granted, but I've watched everything I can on many of them, and those are the dudes who look like they can plug in to this offense. The Nebraska kid maybe deserves to be listed, I do like him very much, but he's got a bum knee which to me is a no-go.
Of those listed above Warren & Loveland are probably off the board by 20. Meaning you will have teams looking for pass threat from that position considering Arroyo and Taylor. And I have Arroyo over Taylor because he is extremely fluid in space. The boy has skills. But teams are going to be into Taylor and Ferguson by round 2 in my estimation, and I doubt either makes round 3. Only reason Fannin makes round 3 is because he had a subpar Senior Bowl week (they moved him around, granted, like backfield usage) and then ran a very average 40 time, which I think given his size he needed a good 40 to compete with the boys up top in this class. From there you have Gadsden who rubs me the wrong way in his run blocking, I don't think he's particularly willing which to me is a big fucking concern even for a pass game threat TE.
So maybe I'm wrong. We will see soon thank fuck. But I think Ferguson is underrated given positioning on media boards. What he offers is going to be valuable to teams.