I think when comparing the two players, it makes the most sense to look at how good they are now and how good we think they'll be in the future.
When you're comparing potential no it doesn't.
I interpret the OP's point to be
Stiemer's potential and if that is equal to Perk (or better)
now. Not if Stiemer's potential will be equal to Perk's or someone else's best stretch of ball.
This is relevant because Perk was traded last year, and many people flipped because we haven't had a true (reliable) center since.
In other words - does Stiemer in the not-too-distant future represent what C's fans feel we lost in Perk? Or is he better than that? Or worse?
To answer this very easily, I look at both players now. Stiemer's advanced metrics support that he is better than Perk
right now. At the very least we can say the Stiemer is 90% of Perk right now. That is a conservative point of view. When you take into account that Stiemer is: (a) still a rookie, (b) not practicing due to injury, (c) not completely healthy, (d) not getting the same minutes as Perkins, it is hard not to say that Stiemer is just as good.
So my answer is, Stiemer's potential is at least equal to Perk.