He is the best man for the job 

=He is the best man 

这里的for能不能换成to

以上介词表示“适合，胜任，担任意思”

She's the very person for the work.
她最适合干这项工作。

Milk is the natural food for young babies.
牛奶是婴儿的天然食品。

sb is the best man for sth某人是某事最佳人选

I'm the best man for the job, I hope.  

希望我是那份工作的最佳人选。

He is without question the best man for the job.  

毫无疑问,他最适合干这份工作.

备注：for sb和for sth区别

(1)for sb(表示对象)为了，给，对于(英文解释：If something is for someone, they are intended to have it or benefit from it.)

Isn't that enough for you? 

那对你来说不够吗？

I have some free advice for you.  

我可以为你提供免费咨询。

(2)for sb为…喜欢;对…适合 (英文解释：If you say that something is not for you, you mean that you do not enjoy it or that it is not suitable for you.)

Wendy decided the sport was not for her. 

温迪认定这项运动不适合她。

Not for me the settled life.

安定的生活并不适合我。

(3)for sb对…来说 (英文解释：You use for when you make a statement about something in order to say how it affects or relates to someone, or what their attitude to it is.）

What matters for most scientists is money and facilities.  

对多数科学家来说，资金和设备是至关重要的。

For her, books were as necessary to life as bread.

对她来说，书就像面包一样，是生活必需品。

(4)for sth供…之用;为…所需 (英文解释You use for after words such as 'time', 'space', 'money', or 'energy' when you say how much there is or whether there is enough of it in order to be able to do or use a particular thing.）

Many new trains have space for wheelchair users. 

许多新型列车为坐轮椅者留有空间。

It would take three to six hours for a round trip.  

往返行程需要 3 到 6 个小时。

   这里的 for 表示“适合”的意思，不能换成to。如：She's the person for the job.她就是干这份工作的合适人选。（《牛津 外研社英汉汉英词典》）