After the Combine they had him graded as a 5.3 which equated to a ...
"5.20-5.49 NFL backup or special teams potential"
in their grading system.
I think he was tied for 18th on the DLine rankings.
And if you use that grade, a rank of 102 (which is what I think the "make your mock" really has him ranked at) would make sense by their strange ranking system.
Of course, as of today, when you go look at the DLine grades, they've made some "updates".
Donald is now a 6.3 and ranked second (behind Clowney) in the DLine rankings.
I would suspect the "Make your mock" section will eventually update as well.