Haven't watched a lot of Valimaki since the trade but in the games against Calgary, a couple of things stuck out. The increased ice time & responsibility has done wonders for his confidence and unsurprisingly, restored his offensive game. But at the same time, he's still prone to some terrible defensive miscues and it's those mistakes that would have seen him remain in Dutter's doghouse and a semi-permanent healthy scratch.
For better or worse, Calgary's defense has a pecking order and Valimaki, by his own deterioration in play was near the bottom. And what Darryl Sutter wants from his bottom pairing defensemen is the complete opposite of Valimaki's current game. But even without Sutter's dinosaur antics, it just wasn't going to work out in Calgary after Valimaki's back-to-back leg injuries. His confidence was shattered and he badly needed a change of scenery. And going to an openly tanking team that could give him all the minutes and opportunities he wanted without any repercussion was exactly what he needed to get going. It's just bad luck (and some questionable drafting) on Calgary's part.