When a team plays with 10, the only smart option is play with a low block and defend till a mistake happens, a set piece or a counter attacking opportunity presents itself. That is exactly what happened that game and falled into west ham play book. West ham are well organized defensively and taking out that extra man for them, just meant that their counter won't be as effective.
-I said that west ham going down to 10 men allowed them to continue playing block. West ham is a team that more often than not play a low block especially against a possession oriented team.
-Of course taking a 2-1 lead in the 43rd minutes doesn't guarantee a victory, but you know what it does a guarantee?? (Unless that team is winning in aggregate in a cup competition

) For the team that is loosing to be more agreesive in the attack and change their defensive shape. If that happened, it would have favored chelsea who struggles against a team with a low block.
-Liverpool winning with 10 men is relevant because it shows how strong a team they are and also, that when a team get a player sent off, it doesn't mean that they are destined to loose.
- playing the last 30 minutes with 10 men, doesn't change the holistic outlook on whether a team is strong or not. You admitted that west ham is a strong team, so even if they loose 1 player, they suddenly become a weak team? That isn't how football works. Sometimes when a team goes down to 10 men, they become stronger in one area of the pitch e.g. defensively. 1 player will only affect their defensive shape if they don't fill that hole left from the player that got carded. So, west ham was still a strong side because only their attack was blunted because of that card and their defense still remain resilient or even more resilient than without the card because their objective was clear when that event happened.