Meaning of 어야 되다 with 이다

Question

I am quite confused with the precise meaning of 어야 되다/하다 with the copula 이다. I know that 어야 되다/하다 means an obligation or that a certain condition has to be met.

But consider the following examples:

축구 정말 잘 하니까 선수여야 돼요.

How should I understand this example? Basically, it means "You play soccer so well that you must be a professional player." I see two possible meanings:

1. You play so well that you must become a professional player.
2. You play so well so that I guess you are a professional player (you cannot not be a professional player).

Similar example:

너는 너무나 아름다우니까 모델이어야 돼요.

Meaning:

1. You are so pretty that you ought to become a model.
2. You are so pretty that I am certain that you are a model.

Which interpretation is the correct one ?

(and, as a bonus question, how would I express the other meaning in Korean?)

Answer 1

In Korean, "-해야 되다/하다" can only mean an obligation, that is, "it is required that you do X".

So, "선수여야 돼요" can only mean "it is required that [someone] is a professional player." For example, I think the following is acceptable:

축구를 정말 잘 하는 사람이 필요하니까 선수여야 돼요.

= We need someone who's really good at soccer, so it must be a professional player (not just anyone).

To mean "from the evidences, I must conclude that [someone] is a professional player", you can use constructions like:

축구를 정말 잘 하는 걸 보니 선수인 것이 틀림없다/분명하다.

(or) 축구를 정말 잘 하는 걸 보니 분명히 선수다.

= Since he's so good at soccer (literally, "After seeing that he's so good at soccer"), he must be a professional player.

Similarly, the second example can be:

이렇게 아름다우시다니 (모델인/모델이신) 게 틀림없습니다.

Or slightly more conversational (and rather cheesy):

이렇게 아름다우시다니 모델이시죠?

• There's no reason to add "너/당신" unless it's ambiguous.
• "너무" is either "very" or (traditionally) "too much". I think it's possible to use "너무" here, but the word is overused, and "이렇게" sounds more natural, because you're describing something right in front of your eyes.
• "-하다니" means something like "since (I can see / I just realized) X"