It's a very fair question. Unlike players who you can watch at their craft (thus why we can say someone like Aho is no good), it's very hard to see head coaches at theirs. You aren't on the bench to hear what they say or in the locker room just the same. So anyone judging coaches is more of an exercise in conjecture than judging players (or even GMs as you can see their trades, picks, and signings).
As a result my feelings on Lane are opinion based on the limited information we have on him. And for me I don't get the sense he outwits/outthinks other coaches out there. With Trotz it always felt like, "He's got this" and you don't have to worry about the coaching part of the Isles. And the same way a team picks up confidence and plays better when they have confidence in their goaltender, I think Lane in lacking in that regard.
This is a very experienced roster with good chemistry and work ethic so any coach will have that as a base when they come in on day 1. From there it's a coach's job to get the team to play to their potential, and while no one is confusing them with the Bruins, does anyone here honestly believe this team has been playing the best it can all season? That alone should tell you that Lane might be ok, but he isn't good enough.
From a tactics standpoint - I think he has that element. I love the fact that he has the D more aggressively and not playing it too conservatively, whether it is D jumping in the play more or challenging forwards in the neutral zone. IMO, a sign of a poor coach is when the team does not buy into a system or identity (Green and the Canucks) or when there is a lack of structure (Boudreau and the Canucks) - I guess with Green it is more of losing the room and no longer having trust from the players. We are not seeing that here.
You are right we are not in the room or on the bench to see how Lane is doing. From comments we've read from players - we know Lane is more passionate and vocal than Barry was.
You are correct that the team has not played to its potential, but to be fair many here -you included- have criticized that the Isles are a mediocre team and so maybe they are exactly where they should be an above-average team playing above 500 hockey nothing more. I don't think that's on the coach is the roster or personnel.
Lane definitely has them all pulling in the right direction and doing it undermanned and that is to his credit.
I don't know if he is the right person for the job - I need more time to evaluate, like making the playoffs and then the playoffs.
Roster-wise - I think the team is still hurting from not replacing Toews AND missing that one more piece upfront... I think both those things address the PP and strengthen already a good team at even strength.
Horvat might be that piece upfront, but Aho and Romanov are not that piece on the blueline... hoping for one more move that gives this roster a bit more.
IMO, I think this team secures the 7th spot and faces Carolina in the 1st round. From there we'll see if Lane can outsmart a very good coach in Brind'amour.