First, I think Elmore has proved his value as an elite blocking back. The coaches know where he can have the most impact — and him switching to being the 4th DT? Nope.
Second, the issue at DT (behind the top 3) is that we can list some names from the roster ( as you have done), but these candidates have not shown much potential to date. Harper and Grosvenor each have exactly 1 tackle to their names. What have you seen from them (Spring game, or otherwise) that gives you confidence in their ability to step in? How highly regarded were either when recruited? In contrast, Williams, Black and Ruff each showed something early in their SU careers - Ruff is 300 LBs with elite speed for a DT, Williams has strength and agility, Black has DE agility (playing as a true frosh) and has added size and strength.
Okechukwu or a newbie — maybe, but you are stretching a tad (likely ... might be).
"Elite?" You're significantly overstating his capabilities / contributions. Elmore hasn't shown much as an offensive cog -- not as a short yardage runner, or as a goal line threat. He's okay as an in-line blocker [moreso than as a traditional lead blocker, IMO] -- largely because he's borderline OL sized. I'll defer to the coaches, but I think you need to revisit bnoro's post above. Outside of blue chip programs, where they recruit NFL-archetype DTs every class, DTs are at a PREMIUM at other schools. It's the hardest position to recruit, which is why the notion that he makes a bigger impact as a fullback than he would as a 4th DT isn't a very compelling argument.
Also, I think you are using revisionist history with your assessment of Ruff. He was recruited as a three-star inside LB, but lacked the lateral mobility for our system. He didn't do much for his first couple of years -- until he got a chance to get more PT last year after he grew into a DT. What did he show early in his career?
Black got forced to play -- and part-time start -- as a true frosh. He was okay, but he wasn't physically ready and got housed by numerous teams. Now that he's a couple of years into his career, he's much more equipped to play than he was early on.
To your point about the newbies -- you contradict yourself by pointing to McKinley Williams as an example of a player who flashed early, while later discounting the possibility that Okechukwu, Rondi, or any of the newbies might do the same. By the way, Williams was forced to fill a role in the two-deep as a true frosh due to lack of depth, and played pretty well on the interior despite weighing 255 pounds. That's about the same size [and lighter actually than some] of the newbies. So I wouldn't write them off merely on that basis alone.
This shouldn't need to be stated, but OF COURSE young players are unproven until they have a chance to play. And sometimes, those guys have to wait a couple of years to crack the rotation, or to mature physically, etc. There's nothing wrong with a guy not playing a prominent role until they are a third year sophomore. Which is why a player like Harper could be primed to take the next step. He's been in the program now for several years, he's acclimated to college ball, he understands his assignments, and now he's ascending into a more prominent role. That's generally how things work in college football -- him not playing much last season when we had a four player DT rotation that garnered the vast majority of snaps [including an NFL draftee] isn't as indictment, it was a function of depth ahead of him. He's now needed to produce -- we'll see if he's up to the task. He'll be given every opportunity -- and if he falters, then next man up.
That's what happens at the collegiate level -- players graduate, attrition happens, and younger players step into more prominent roles.
Nothing is a given. Harper is unproven. The others are new. We'll see how they perform once practice starts. All we need is one of them to emerge. I'm guessing that we'll see two players emerge as platoon depth behind our three proven commodities at DT, and concerns about depth will go away.
