I'm going to take a wild guess that you mean "hold" at Case, cause so many, many people have been put on 'hold' at case (myself included). Most of us, it seems, did not write the optional 'why i want to go to Case specifically' essay, and have scores above the 75th. So I think it's a yield-protection thing.
What I mean is : They are mostly full, right? Let's say hypothetically they have 10 percent of their seats left. They know that it is late in the season, and many people who were initially interested in Case have now made other plans, but not withdrawn. They don't want to have to admit 30 people to find one that will fill a particular seat. They still want the best applicants they can get. So what do they do? They send "hold" letters out to a wide cross section of 'attractive' applicants, to get their reactions. Some of these "hold" people write back with letters of desperate interest.
Now they have established a pool of people with good numbers who have shown a greater likelihood of matriculating if accepted.
That way they accomplish two things: They increase their "deny" ratio ultimately, because they deny all those people who don't respond to the Hold letter. They increase their acceptance-to-matriculation ratio, because they admit people who have already shown that they will seriously consider attending.
This is all majorly hypothetical, but I think it makes sense. Anyone agree/disagree?