I wouldn't quite go there. Based on some previous comments about McBain, I paid closer attention to him this game, especially away from the puck. He has a much higher hockey IQ than Corvo, and for the most part, was in the right positions or reacted to Joni's wandering by covering the right spot. Corvo wouldn't do that. IMO, he also has the best offensive instincts of the defensemen. By that, I mean he really knows when to jump into the play offensively and get a scoring chance and when to hang back. He does this very well IMO and the goal he scored tonight is an example of that. He's also good at walking the line and getting off a shot or pass (vs. just blasting it). His passes are usually pretty good and much better than Corvo's as well.
On the negative, his skating and strength looked pretty bad to me and he's not very strong on his skates. Not sure who it was, but someone on a GDT a few days ago said he looked like dog **** (or something like that) and I can see why. In fairness, this was against a pretty big and tough team, but he was not able to win a lot of puck battles and was knocked down quite a bit even when it wasn't a physical play and just wasn't strong on his skate. While they didn't lead to goals, he struggled a lot to try and get the puck out of the zone. I am guessing that is why he was a healthy scratch at the start of the last two seasons as in training camp, things like condition, strength etc.. might show up more than hockey IQ/offensive instincts.
I really think that if McBain would work on his strength and skating that he could be a solid top 4 defenseman. IMO, He's got the talent and the IQ to do that