No need to over react.

Let's review the lost to Boston.

Marner = playing with sore ankle
Nylander = 3 missed games with a headache
Matthews = 3 missed games with a tummy ache
Woll = benched 3 games and injured 1 game
McMann = injured all series
Reaves = sadly 5 games played instead of 5 healthy scratched games
J.T. = not captain material
Keefe = ugh !!!

Matthews only missed 2 games
Reaves did not play that bad and played very well in game 1 & 2
Why is JT not captain material? I thought he played hard the whole series

Matthews wasn't close to be healthy in game 4 (left the game early).
Reaves was on the ice on a couple very key goals against.
What did JT do when all that drama was going down on live TV on the Leafs bench.

It's not a big deal that things got heated on the bench between the star players (Marner throwing a tantrum after is another thing). People want them to show more emotion in their exit interviews when it doesn't matter.

JT is captain material, he didn't end up captaining two teams by accident. That being said I don't think that he's the best captain for the Leafs for a couple of reasons: 1) Matthews and Marner seemed to have always looked up more to guys like Marleau and Thornton more than they do Tavares and 2) it seems that the Leafs played harder for Rielly when he was injured during the regular season last year and for Matthews this post-season then they did for Tavares when he was injured during the MTL series. I'm sure he's still respected by all in the locker room but I think the role of alternate captain would suite him better. I don't think Matthews is a better leader than Tavares but I think it's time to charge him with that role and hope that he can step it up. Giving the C to Rielly or anyone else will probably just lead to division in the locker room.