The 4-3-3 has been broken this season as the legs have fallen off the midfield. It's a very highly strung tactic and very unforgiving if something isn't right. In this case, it's been the press. No press and the high-line just gets picked off as we've seen time and time again. It's been open season in some games. It's made our good defenders look bad, when it's actually been a lack of intensity in the middle that has let the whole system down.
Of course, some were starting to question the leadership, but I suspected a change like this was coming. We can't chop and change every few games if something doesn't go quite right, but after several poor performances in a row where we've leaked goals, Klopp knew it was time to change, and the 4-3-3 wasn't going to fix itself. At this point I suspect it's a personnel issue and I reckon we'll see a fair bit this 4-4-2 until we can get some energy into midfield.
Klopp picked the perfect time to spring a surprise as it left Pep pretty flummoxed and by the last 15 minutes they'd completely run out of ideas. It's been a very long time since we saw a Man City team so unthreatening. They had an XG of less than 1!