You don't know Horton. He's won a cup, maybe he wants something new? Maybe Boston wanted Iginla? This contract might look bad in year 6 and 7 - MIGHT. Up to that point, it's a good contract. After that you'll have to wait and see.
He was healthy most of the year until the end too.
I believe he wasn't playing when they won the cup. He missed the entire series vs Vancouver from what I recall. Yes he's got a ring but he doesn't really know what it's like to play in the final series and win. And you're right, I don't know him... but it's still pretty weird that you would leave a cup contender for a rebuild right now. I mean, why the hell would you do this? It just reeks of cash grab.
As for his contract, I wouldn't touch it with a ten foot pole. That guy has had his bell rung so many times that it doesn't take much anymore for him to get knocked out for weeks at a time. It's not the years its the mileage. He's damaged goods and there's absolutely no way this guy is going to play out that contract. I loved his style of play and would've loved to have got him years ago but he's not worth that money or term.