何をではなく、『誰が』

I was so surprised. 

I would like to talk about an English training product.  
The product which was released by former collogue is becoming very popular in my company.
Actually,,, I didn't think that product is so nice, since it hadn't gotten high rating and my subordinates taking the service didn't told me it was nice.

Finally I was wrong. That product is in big demand.
However, what made me surprise is A PERSON who introduce the service.

He is just one member of human resources.
But he tried to share a lot of information via company tools such as SLACK group.
He is very famous and looks trustworthy person.

That service wouldn't be so famous unless he had informed to people.

I saw that WHO DID is more important than WHAT IS.