This phrasing suggests that the only objective that Patriot had was to defend itself, which it failed. However, Patriot system in question was also tasked with defending a lot of critical objects in Kiyv, all of which have not been hit.

Any system can be saturated and overrun. To make an honest assessment, we need to know exactly how many Patriot systems were on the ground, and how many targets were they tasked to protect.