My issue stems from kicking thieves asses but rarely killing them, due to their large amount of "Lol, cya" type skills.
The only time I could really catch them was when I knew they were dumb enough to run in one direction, and simply dropped ground AoEs in the path they were running. But that was all luck, and only being able to finish someone if you're lucky is annoying.
(Then again, telling my flesh golem to charge in a completely random direction and hitting Allanon while he ran like a tool was EXTREMELY satisfying)