We were missing three of our most important players, Allison, Henderson and Mane (not even going to include Thiago). We were unlucky to concede three deflections. We also came up against a team that we probably underestimated. So, I don't think we need to reinvent the wheel based on last night.
On the other side, we played really poorly, bar maybe Salah and Jota. And, as others have said, we haven't been great since about March. So we do need something. I reckon we're short a top quality CB, hopefully Jota will perform for us(he provides a different style from what I can see) and will allow us to rotate the front three without a huge dip in quality, and just need to get a couple of those players back playing again, and we'll be well capable of being at least in the top two again.