Set development targets and offer appropriate support to ensure employees can reach their goals. Support out-of-work development activities as well. A more-rounded employee should be better for the business.

That is very important. Training and personal development at employee level is a key requirement for the employers. With the rapid change in business requirements and technology, personal development and training helps employees to be on pace and it directly improves productivity,
Also, that increases loyalty as well.

Football is an individual skill while office work is related to your employer. For example if you are too good for a process for an organization, you might be misfit for other one. Hence, employer should invest on other skills as well.

Before someone becomes a professional baseball player they have had literally years of development doing/practicing the same thing they will one day be doing professionally. They play as a small child and they are coached and developed by mentors and trainers rigorously. If they really show promise, there is even more training available.

the situation for employees and managers is not the same. Other than playing make-believe as a small kid, there is little chance to learn and practice the skills needed to succeed in a work environment. The best learning happens as a combination between formal instruction and practice. For people in an office setting, this needs to happen on the job.

Why is it not consistently happening? Because of press of the daily work. To continue your sports analogy, you would never take a player out of the winning game to send them to a training session. Likewise in corporate world, leaders are loath to take a valuable employee off a project to send them to training or to put them in a new role as a novice (so they can learn) when they are an expert in another field.

The way to ensure that employees are trained as rigorously as athletes is simple but not easy. There needs to be a cultural shift to make training a part of the way the company does its work. and there needs to be tone from the top to ensure it happens

Taking the example of the football-player. Is it true that they are self-motivated, but on the other hand there are also enough examples that after their career they don't find a job to keep up their lifestyle. There are examples that these stars end up in poverty.

I assume we all can agree that continuous learning is imperative in changing times. Unfortunately humans often not think that long-term. This based on their character or also their socialization. Employers require an adequately trained workforce, so want to support learning. This with giving them time to study, but also short-term goals and a positive development to foster the different steps on the way.