"We have the best goalkeeper in the league."
Translation:יש לנו את השוער הכי טוב בליגה.
I consulted with my old Hebrew professor about this. (Among other things, she wrote an excellent Hebrew textbook so yes, she's an expert.) Strictly speaking, putting an את after a יש is bad grammar, since את marks definite direct objects, and "the best goalkeeper in the league" is the subject of the sentence, not the direct object. However, it has become common usage, and the old-school grammarians who insist on leaving the את out have pretty much given up the fight. The usage also appears in a few classical sources, so it's not just a modern corruption of the language.
Even so, saying that את is required is a stretch. It may sound old-fashioned to leave it out, but the sentence without את is certainly not wrong.