The loss of Hossa certainly hurt, but I don't think that's what cost them the game. There were a couple bad turnovers last night that led to Corey Crawford being hung out to dry. David Oduya's turnover especially stands out. Getting your pocket picked from behind when you're just meandering around in your own zone is just unforgivable.
In a bigger picture problem, the Blackhawks special teams were horrendous all year. They were completely unable to kill off penalties, and when they had their own power play chances, well, they were just unable to convert. Why is this? I don't really know. They Blackhawks have much the same core they did when they won the Stanley Cup, and they were great on the power play then. Since then, it's not been so great.
The difference might be as simple as Dustin Byfuglien. He was such an integral part of that championship team, with a combination of stick handling, speed, and size that doesn't come around very often. I knew the 'Hawks would regret it when they let him go after the season. Go back and watch those games against Philadelphia in the finals if you can. Byfuglien did much more than his fair share in winning those games. He just dominated those games with his size and stick. There was no separating him from the puck, and unlike, say, John Scott, he had enough hockey skills to do something great with the puck once he had powered his way through.
The Blackhawks have been a total finesse team since he left. They very rarely outhit teams, and only had a player with double figure hits a small handful of times all year. I'm not saying you have to be a team of thugs to win the NHL, but there are times when some physical play is necessary, and the Blackhawks just don't have the players to do that. If I were Scotty Bowman,* I would look awfully hard at bringing Byfuglien back, or somebody along those lines. Maybe a few enforcer-type players like that. The skill players are definitely there in guys like Toews, Kane, and Hossa. Their defenseman are great. The goalies are good enough. They just don't have anybody that can keep the team from being worn down physically.
*Please, take this all with a little grain of salt. Just like I called myself a fool for ever thinking that Larry Bird was maybe misguided in some of his basketball decisions with the Pacers, I'm sure Scotty Bowman has more hockey knowledge in his pinky fingernail than I do in my whole body. Still, I gots to call it like I sees it.
Just like Wendy's asked in the 80's, I'm asking you, Scotty. Where's the beef?