Which is exactly why he left it so late, because the players on the pitch had already got into a good rhythm and looked increasingly likely to score. Southampton were on their heels.
And it took Sturridge no time at all to get into the flow.
Yes, of course the system was working. On-field arrangements are designed to stop goals and create chances, under the presumption that individual players will convert the chances created by that arrangement. Klopp's arrangement was succeeding in stopping goals and creating a lot of chances. You don't just change it because the finishing is off, you trust that the players will continue the trend of creating good chances, and then finally convert one. It's not so wacky to trust that your elite professional attackers can put one in the back of the net after creating enough good opportunities.
This comparison is redundant because a bulk of shots on target doesn't automatically equate to a good volume of stonewall opportunities. i.e. against Burley, virtually every chance was an attempt outside the box. Against Southampton we created more gilt-edged chances than against all of United, Burnley and Spurs combined. We created *none* against Burnley, one against United after Klopp's Lallana substitution, and two against Spurs, one of which was incorrectly pulled back for offside.
On the other hand, how many legitimate chances did we create against Southampton? Well in the first half Mane was through on goal, and then had another great opportunity inside the box that was saved. In the second half Coutinho horribly fluffed his lines when facing the keeper and should have buried it, Firmino completely fluffed it too, and then Clyne somehow missed a header from right in front. That's five great chances in one game, three of which came in the second half when we were much improved. Our performance was not remotely close to crying out for a substitution, it would have been a substitution for the mere sake of it, 'because that's just what you do when it hits the 65th minute mark'.