I'm not sure where the perception of poor sportsmanship came from, I guess that's not really the right choice of words. I'm not really sure how else to phrase it - it's a honestly kind of a complicated feeling. Sour grapes? Even that might be too strong of an emotion to project, but.. I don't know..
The decision to go to Boston in the first place is obviously just a business decision - no fault in that, that kind of thing just happens in sports, it doesn't take away from the appreciation of anything he did as captain of the Blues.
I don't follow the Bruins under a microscope, so I don't know anything about line chemistry or who the better options were down the lineup - but it did feel kind of bad to see him in the press box, especially against his former team. I was kind of hoping to see him out on the ice throughout the entire series, even if keeping him out maybe didn't necessarily mean icing the best lineup. Obviously I don't care if they don't ice the best lineup.
I did really like Backes as captain, so I suppose in my mind, at the beginning of the series, I envisioned him playing the entire series (even in limited minutes), competing hard, with a poignant handshake/congratulations at the end.
When I didn't see things play out that way, I perceived it negatively - even if there probably was some behind the scenes congratulations, etc.
It just kind of looked like things petered out; he didn't play, and then you didn't really see anything from him at the end, which I found disappointing.