I don't know if I'd go that far. This game was mostly about finishing. Spurs did not get convincingly outplayed today like they did last week against City. The chances were basically even. Spurs were much the better side for most of the first half and if they convert one of their several half-chances in the first half it's a very different game. United's goal in the second half came basically out of nothing.
That said, Poch isn't blameless today. The LB situation is a problem. Ben Davies is a decent PL player but he's frequently a liability against top-class opposition. A fit Danny Rose would have helped a lot today. Poch's tactical switch to take Davies off totally backfired. Playing Moura inside and Vertonghen as a wing-back made no sense. Vertonghen isn't fast enough to play there. Moura's dribbling is wasted in a congested midfield, Spurs had no width on the left, and United always had an outlet into the space behind Vertonghen. If they were going to bring Lucas on, they needed to play him wide and let him run at United's fullbacks, who were already both on yellow cards.
It also seemed clear that Kane was well below 100%. I understand it's hard to drop him, but he seems well below full fitness, Spurs have depth at the attacking positions (they left Lamela and Lucas on the bench), and they were fine going forward without him against Chelsea.