You can use present simple or past simple in this situation. You would generally use the present if the results of the success are still apparent. The sweat on his brow shows how hard he is trying. [you can see him] If it's about something in the past, you might use the past. The sweat on his brow showed how hard he was trying. [you can't see him] But if you're looking at a picture, for example, you would use the present. The sweat on his brow shows how hard he is/was trying. [you can see him in the picture] This is because it's always true in the picture so it's like a general truth. We often use present tenses to talk about the past, such as when we describe a film or a book, or tell a story or a joke.

I don't understand what you are asking. Sorry. Do you have complete examples of what you want to know about?