Is it easier to learn a skill or to have to unlearn something and re-learn something. This has huge impacts as we have to learn and unlearn things all the time.
Professional football has some unusual quirks. One is the idea of the "coaching tree". Essentially, when a coach is very successful, people hire his direct reports. If that person is successful, then people hire their reports. What happens over time is that all coaches can be traced back to 2 or 3 people who started the whole thing.
There is one exception - Bill Belichick of the New England Patriots. Very few of his coaching proteges succeed. I recently read an interesting article that offered an explanation. The hypothesis is that Belichick took a really bad team and built it from the ground up. In a previous stop, he wasn't successful. The difference - when he was successful, he had to teach people his system. When he wasn't, he had to get people to forget the old system and then teach his system.
It raised the question - is it harder to learn or to forget and re-learn?
I find it fascinating because all the data shows that skills and knowledge is becoming obsolete faster than ever. Which means as professionals, we are in a constant state of re-learning. But if that is harder, than maybe we should be much more mobile in our careers and focus on moving so we can learn without having to re-learn.
Where it impacts managers is when evaluating a team - either a new team or a team of experienced people when you sense a business shift is coming. Who are the people you should keep? If you will only be successful with people who have to learn (not forget and re-learn) that would signal you need to terminate people. If re-learning works just as well, it makes the case for keeping existing staff.
Maybe - probably more likely - is that some people are capable of re-learning more than others. Managers have to find a way to identify these folks, because they will be the difference between success and failure.