I honestly don't know one way or the other but it could be because of the offense he plays in. They may not utilize their TEs or the passing game in general but like I said that's just a guess. It's hard to gauge the potential of HS TE prospects at times imo. Ethan Wolf didn't put up great stats in HS because of the offense he played in and he has turned out to be a great player for us thus far.
Oliver seems to have the potential though. He's a good athlete with good size. He's the kind of guy the coaches can mold into what they are looking for from their TEs bc of the skill set he brings to the table. You never know...he could end up being the next Eric Ebron who was also a 3 star coming out of HS. They're very similar looking prospects coming out of HS:
Kyle Oliver
Eric Ebron