A buddy of mine who watches the Portland WHL team religiously thinks we've got a good d-man in this signing. So I'll take his eye-witness evidence for now!
As a Winterhawks fan, I think you've got decent potential being made from nothing here.
I've liked Rutkowski quite a bit. He's a two-way defender who'll always be able to contribute. A bit of a jack of all trades type of player...he hits, defends reasonably, and has good offensive talents. The biggest thing that's improved since his draft year has been his own end play. He used to lean more offensively before.
The biggest issue, and it still is, is his consistency. It's dogged him since he was drafted. He's been absolutely amazing at times, but near invisible a week later. And this is an issue if you're a man in a boy's league and doing this. Fair enough, he's got Wortherspoon, Pouliot, and Jones who also drown him out a bit if he's quiet, but it still is problematic when you can vanish every once in a while.
Realistically, he's probably a 6th-7th D type of prospect with the possibility of going a little higher if he can work out his consistency issues. He's got a lot of tools with him, but unless he puts it together on a regular basis, it's likely that he'll be the type of player who gets rotated in and out. There's a decent chance he won't and he'll just become a "good AHLer".
Good move by the Sens though. These are the type of players you should be developing in house. Getting it for free is nice.