You know, this phenomenon is rife in the saxophone world, with which I'm more familiar, too - superb technicians with poor communication skills and even poorer chops at estimating how long a project will take to complete - which of course often depends on how long a prior project they are working on will take to complete.
As one who often has problems estimating how long it will take to complete arranging/composing projects, I can sympathise, so I can't be too hard on these technicians. However, where I can be, and will be, hard on them is in their inexcusably poor communications. I have found that, as long as a client is kept informed of the progress (or lack thereof) of a project in real time, they are pretty much understanding. This is Business 101.
What I fail to understand are technicians who continue to include this basic and fundamental action as a routine part of their work day - a time set aside each day to communicate with clients. In this day and age with clients from more than one generation, now, of must-have-it-yesterday types, it just doesn't make sense not to give your communications a high priority.