There is not such person as "too smart engineer". Picking too much on their plate may be compensated by positive reinforcement when the task is complete. Adding

There is not such person as "too smart engineer". Picking too much on their plate may be compensated by positive reinforcement when the task is complete. Adding too much complexity to systems suggests that they are not smart enough to understand it makes extra difficulties for no gain. Inconsistent style suggests they did not learn that most of the coding is about reading the code after it was written. Possibly they quickly write and copy&paste code, and do not need to debug it since it "worked once". If they tell something others can hardly understand, and they are unable to explain it, then your engineers need to learn proper writing and explaining skills. All in all, you probably need smarter engineers to manage the team.