I don't disagree that we should have won those games. But I'm not sure an extra DM would have helped. Lots of the goals conceded in these games were due to errors. Individual errors. Nothing can prevent or predict individual errors.You can't just look at one moment. An extra DM might have helped us keep a clean sheet at Spurs. Or see out the win. Who knows. But in the CL we never look like shutting out the opposition. We beat Monaco 5-3 and lost 3-1 away to go out. We lost 3-0 away to Liverpool and lost 2-1 at home. We lost 1-0 away at Spurs and won 4-3 at home. On paper we should not have been losing a two leg game against any of those teams.
And in relation to the Spurs game, we actually lost control after we brought in a DM in Dihno. It was a common sense tactical decision to bring in a more defensive player to close out the game. Unfortunately it disrupted our possession, which got Spurs back into it.
What we need is to do better, that which we already do well. Possess, attack, create. Since repeat.