There's a lot of WTF going on in that listing. First, there's a pretty steep drop off from #1 to #25 - a 5.0 for #1 (of which there are four) down to a 3.6 at #25. I didn't even notice until, on page 2, I say Texas A&M listed at #40 (w/ a 3.1). "A&M" stands for "Agriculture and Marine". Second, the rankings "stop" at #112 which is a 2.0 - however, there are still probably 30 more schools listed as "Ranking not published". Third, to have a school like SMU ranked as "last place" (#112) behind some of the other "schools you've never heard of" just feels wrong. SMU gets a 2.0 which, according to their scale, is one step above "marginal". I can imagine that, from a job hunting perspective, it's far easier to place an 3.x SMU CS grad than it is to place a 3.x "University of Maryland - Baltimore County" grad, both now and long-term.
I'm a computer science student and none of your WTFs are WTFs to me. 1) the numbers don't matter much, they're just what they used to rank. they don't have any implicit meaning. Texas A&M is a decent CS program so not sure why you're pointing it out. 2) maybe they didn't want to rank some schools because they didn't have much data on it. plentyo f possible reasonable explanations. 3) I've never heard of SMU (is it Southern Methodist University or Southern Michigan University or something else?) and I've heard of UMBC several times before -- they have a decent computer science program in human-computer interaction and accessibility.