I think he looked good in game 2 of the finals, the one in which he basically led them to the win, but aside from that he was poor. The lack of mobility he had at that time, being rushed back from the quad tear, was really really obvious and he was just a traffic cone on defense at best. Really poor showing, although obviously most of it was not his fault. I don't want to lean on +/- too hard, because it is a very flawed stat, but there's a reason that game 2 was his only game with a positive +/- though.
There were at least a fair number of people who thought he was be a 20/10 guy, or very very close to it. Even Nichols, who obviously doesn't agree with me on this, said he ''hoped he could at least be 70% of what he once was''*. Well, 70% of prime Cousins is something like 19/9/4 with stretch ability. That's a top 50 player, even with poor defense: hell, that's basically Julius Randle from last year (21/8/3). That's super high expectations, and at least a decent enough proportion of Lakers fans believed something like that was likely as to be noticeable to someone who doesn't even visit Lakers spaces very often (me).
*Note that Nichols said hoped, not expected. Just to clarify that in case the thinks I'm misrepresenting him: he didn't expect 70% of prime Cousins, he said he hoped for it, which is obviously different.