A while back, a friend of mine posed that question to me. Is strength a skill?
The answer is: Yes?
Like most things to do with physical development, the answer is a complex one, and I am definitely not equipped to delve into the meaningful details. I don't know much about how the nervous system actually works. But I know, as do most people who have been involved with strength training in any serious manner, that neurological changes (functional adaptations) are as big, if not bigger, a part of improvements in strength as changes in size/quality of muscle tissue (structural adaptation.)
A great example of functional adaptation improving applicable strength is the rapid gains made by novice trainees on a linear progression. Someone completely new to strength training can squat 3 sets of 5 on Monday, Wednesday, and Friday, and go from having a pretty hard time with 135 in the first workout, to an easy session with 145 in the second workout, to an equally easy session with 155 in the third workout. This sort of progression can continue, relatively uninterrupted, for several months (so long as the trainee keeps the bar dihrectly over thuh middle of the fuht.)
It is fairly obvious that in one week, the trainee did not add significant muscle mass or significantly improve the quality of muscle tissue. What happened is that the trainee got better at the skill of squatting. Even if there is no visible improvement in his mechanics, his nervous system is now better at executing the actions involved in a good squat.
Of course, this begs the question, what defines strength? To know if strength is or is not a skill, we need a concrete definition of what strength is.
And of course it's not that simple. These things exist on a continuum. Over the course of 4 weeks of leg pressing, one is not likely to get as much improvement in strength - defined by the load moved - as one will get over the course of 4 weeks of squatting, because there is far less for the nervous system to do in the leg press. It's much easier for the nervous system to perform hip and knee extension without the additional tasks of balancing the weight on the foot as the center of mass moves, keeping the back extended, making sure you don't poop yourself, etc. In order to move more weight on the leg press, a greater degree of structural adaptation would be required.
In the same vein, one will not get as much out of skill development in the squat as they will in the snatch or clean & jerk. The more technically nuanced the application of strength you choose, the more strength becomes a skill.
I guess what I'm saying is, choose your definitions wisely.