'There is an argument to be made' is a common expression in English and means 'it is possible to present evidence that would support the claim', e.g.:
It is possible to present evidence that would support the claim that the team play pretty well.'
Implicit in the statement is fact that you recognise the possibility that there may be other people who disagree with what you are claiming. If you believe that everyone would agree with your claim then you are more likely to say ,'It is indisputable that the team play pretty well'. Of course, the fact that you believe something is indisputable does not stop someone else from disputing it.
A similar expression, which means the same thing, is:
You could argue that the team play pretty well.