Working computer scientists (academics) are definitely not terrible at math. There are a great deal of complicated proofs involved in areas such as complexity theory, algorithms, and data structures. Their jobs are not altogether different from those of mathematicians.
The tight performance bounds for Union-Find data structures are ridiculously complicated to prove given how simple the algorithm is, even in a mathematical sense.
There isn't a lot of theory-building in algorithms, compared to the more traditional fields of maths, but the combinatorics are formidable.
