First picture everyone is marking, good stuff. They might be calling Doherty but they don't actually need him and if anything Moutinho is the closest spare man that could come in a provide an extra body.
Second picture Doherty has started tucking in, Moutinho has took about 3 steps, Neves lost Son and Boly has come to the near post leaving Lamela free.
Third picture Coady has been attracted to Lamela as he was allowed to run off Boly, Bennett caught in no mans land between Kane and Moura where he's either being beaten to the ball by the former or having it drop over his head to the latter and you've got the trio of Moutinho, Neves and Cavaleiro just milling about on the edge of the box letting Son go wherever he wants to pick up the pieces.
Could Doherty do more? Sure he could. Would I say I expect a wingback to be marking someone back inside his own six yard box? Probably not. There are a lot of errors in the defending of that passage of play, Doherty's role only comes in right at the end where he could potentially cover at the last minute and everything else would be ignored but Moutinho and Cavaleiro do absolutely nothing in that whole passage, Jonny does very little above that just standing really narrow until the goes to Trippier, Neves makes an attempt to press Son before he plays it out wide but then completely ignores him as he runs into the box afterward. Ideally I wouldn't want to have my back three man for man very often but there are times when it will and they have to take responsibility, pick up their men and win their individual battles, Boly didn't engage with his, Coady got dragged into the wrong one as a result and Bennett got caught between the two remaining men.
Be interesting to see how much discussion there would be if Doherty had got back in a bit quicker and thwarted Moura's effort only for it to drop for Son to hammer in the rebound, would Moutinho and/or Neves be under the same scrutiny? To my mind they were both far more passive with their tasks in that move than Doherty.
