There were too many times last season where the Isles did not show up to play. In the playoffs they did. They were outmatched quite easily. They played relatively well against the Canes (save for that one blowout), but their best was not good enough to come out of the first round.
With Lee, Horvat, Nelson, and others, there is enough of a veteran presence where shaking up chemistry should not be an issue. In fact, it may light a fire under peoples asses that if the "identity line" can be moved, anybody can.
At this point the "identity line" are 12th forwards on a good team, individually. Together they are a black hole and have not shown an ability to play with other forwards on this team. So yes, I understand chemistry, but for two years in a row, chemistry has produced a mediocre team. Time to change the chemicals.
Matt Tkachuk was a rare elite talent at the time he got traded, and just got better with the Panthers. Unfortunately, we don't have a player like that. Worst part is that we didn't even have the assets to trade for a guy like that, let alone the cap space. Such is life with Lou: load up on gritty old players and ignore organizational depth. There's still a window, but running it back is not an option.